piercing _Corethrina._
Metatarsus longer than first tarsal
joint _Corethra_, Linnæus.
Metatarsus shorter than first tarsal
joint _Mochlonyx_, Ruthe.[391]
[391] Many other genera have been created; these will be found in my
catalogue of _Culicidæ_ in my “Monograph of the Mosquitoes of the
World,” 1901–10, 5 vols., in my “Novæ Culicidæ,” family _Culicidæ_,
Genera Insectorum, etc.
NOTES ON THE DIFFERENT GENERA.
Sub-family. *Anophelina.*
The following Anophelines have been recorded as malaria carriers:--
*_Anopheles maculipennis_, Meigen.
_Anopheles bifurcatus_, Linnæus.
*_Myzomyia funesta_, Giles.
_Myzomyia lutzii_, Theobald.
*_Myzomyia rossii_, Giles.
_Myzomyia listonii_, Liston.
_Myzomyia culicifacies_, Giles.
_Pyretophorus superpictus_, Grassi.
*_Pyretophorus costalis_, Loew.
_Pyretophorus chaudoyei_, Theobald.
*_Cellia argyrotarsis_, Robineau Desvoidy.
_Myzorhynchus pseudopictus_, Grassi.
_Myzorhynchus barbirostris_, Van der Wulp.
_Myzorhynchus sinensis_, Wiedemann.
_Myzorhynchus paludis_, Theobald.
_Myzorhynchus mauritianus_, Grandpré.
_Neocellia stephensii_, Liston.
_Neocellia willmori_, James.
_Nyssorhynchus theobaldii_, Giles.
_Nyssorhynchus fuliginosus_, Giles.
_Nyssorhynchus annulipes_, Walker.
Those marked with an asterisk (*) also carry the larvæ of _Filaria
bancrofti_, as also do _Myzorhynchus minutus_, Theobald, and
_Myzorhynchus nigerrimus_, Giles.
Genus. *Anopheles*, Meigen.
“Syst. Beschr. Europ. zwei. Ins. I,” 1818, ii, p. 2, Meigen; “Mono.
Culicid.,” 1903, i, p. 191; iii, p. 17; and 1910, v, p. 3, Theobald.
This genus contains a few large species found either in temperate
climates or in hills and mountains of warm climates. The type is the
European and North American _A. maculipennis_.
[Illustration: FIG. 399.--Wing of _Anopheles maculipennis_, Meigen.]
_A. maculipennis_, Meigen. This species and _A. bifurcatus_ are
malaria carriers. True Anopheles only occur in Europe, North America,
the North of Africa and in the mountains of India, and one has been
found by Bancroft similar to _A. bifurcatus_ in Queensland. They are
easily told by the absence of scales on thorax and abdomen, and by
the rather densely scaled wings with lanceolate scales.
Genus. *Myzomyia*, Blanchard; *Grassia*, Theobald.
_Comp. rend. heb. Soc. Biol._, No. 23, p. 795, Blanchard; “Mono.
Culicid.,” 1910, iii, p. 24; v, p. 16, Theobald.
This genus occurs in Asia, Africa and South America, Europe and East
Indies. The type is _M. funesta_, Giles, found in Central and West
Africa. Although structurally there is not much difference between
this genus and Anopheles, they differ greatly in appearance, and
there are usually a few narrow curved thoracic scales projecting over
the head, whilst the wing scales are much smaller in proportion,
and the wings more uniformly spotted, always so along the costa.
_Funesta_ and _lutzii_ are undoubtedly malaria bearers and also
_rossii_.
Genus. *Neomyzomyia*, Theobald.
“Mono. Culicid.,” 1910, v, p. 29.
A single species only occurs in this genus, _N. elegans_, James, from
India. In this genus, which is near to Myzomyia, the fourth long vein
is very near the base of the third, and there are outstanding scales
on the prothoracic lobes, and there is a marked tuft of dense scales
at the posterior angles of the head.
Genus. *Cycloleppteron*, Theobald.
“Mono. Culicid.,” 1903, ii, p. 312; 1903, iii, p. 58; 1910, v, p. 33.
Two common species only occur in this genus, _C. grabhamii_, Theob.,
from Jamaica, and _C. mediopunctatus_, Theob. (Lutz., ms.), from
South America. The chief character is the presence of large black
inflated pyriform scales on the wings. The palpi are densely scaled.
Neither have been shown to be malaria bearers.
Genus. *Feltinella*, Theobald.
“Mono. Culicid.,” 1907, iv, p. 56.
A single species, so far only found in this genus. The basal lobes of
the male genitalia of two segments, the prothoracic lobes with dense
outstanding scales.
The species, _F. pallidopalpi_, Theob., occurs in Sierra Leone.
Genus. *Stethomyia*, Theobald.
“Mono. Culicid.,” 1903, iii, p. 13; 1907, iv, p. 59; 1910, v, p. 35.
Four species occur in this marked genus--one _S. nimba_, Theob., from
British Guiana and Para, another _S. fragalis_, Theob., from the
Malay States, _S. culiciformis_, James and Liston, from India, and
_S. pallida_, Ludlow, from India.
The former may be a malaria carrier, for Dr. Low says: “Malarial
fever is got amongst the Indians and often of a severe type. In
that connection it is interesting that in the interior, at a place
called Corato, I got an entirely new Anopheles in large numbers.” The
genus is easily told by its unornamented wings, flat head scales,
mammillated prothoracic lobes and long thin legs.
Genus. *Pyretophorus*, Blanchard; *Howardia*, Theobald.
_Compt. rend. heb. Soc. Biol._, No. 23, p. 705, Blanchard; _Journ.
Trop. Med._, v, p. 181; and “Mono. Culicid.,” 1903, iii, p. 13; 1910,
v, p. 36, Theobald.
Forty-four species come in this genus, of which _Anopheles costalis_,
Loew, is the type.
This genus is found in Africa, India, Europe and in Australia. Three
species are proved malaria bearers, namely, _P. costalis_, Loew, _P.
chaudoyei_, Theob., and _P. superpictus_, Grassi. Members of this
genus can be told by having narrow curved thoracic scales, hairy
abdomen, and much-spotted wings.
Genus. *Myzorhynchella*, Theobald.
“Mono. Culicid.,” 1907, iv, p. 78.
In this genus the thorax has distinct, narrow curved scales, and the
abdomen is hairy, the wing scales broad and lanceolate, and the head
with broad scales not closely appressed, but not forked or fimbriated.
Five species are known: _lutzi_, Cruz; _parva_, Chagas;
_nigritarsis_, Chagas; _tibiomaculata_, Neiva; _gilesi_, Neiva; and
_nigra_, Theobald. They are all recorded from Brazil, and _nigra_
also from Mexico.
Genus. *Manguinhosia*, Cruz, in Peryassu.
“Os Culicideos do Brazil,” 1908, p. 112.
A single marked species from the Brazils. The thorax has piliform
curved scales, and some narrow curved and flattened ones on the
sides. Abdomen pilose, except the last three segments which are
scaled. No tufts of scales on posterior femora.
Allied to Lophoscelomyia, but at once told by the absence of scale
tufts on the hind femora. _M. lutzi_, Cruz, Brazil.
Genus. *Chrystya*, Theobald.
“Rep. Sleeping Sickness, Roy. Soc. Eng.,” 1903, vii, p. 34.
A very marked genus in which the hairy abdomen has very long, dense,
hair-like, apical, scaly tufts to the segments. A single species only
so far known, _C. implexa_, Theobald, from Africa (Uganda, Sudan,
etc.).
Genus. *Lophoscelomyia*, Theobald.
_Entomologist_, 1904, xxxvi, p. 12.
A single species only, from the Federated Malay States. The hind
femora have dense, apical scale tufts; the thorax long, hair-like
curved scales; abdomen pilose, except the last two segments which are
scaly; wings with broad, blunt, lanceolate scales.
Genus. *Arribalzagia*, Theobald.
“Mono. Culicid.,” 1903, iii, pp. 13 and 81; and 1910, v, p. 48.
Two species only occur, found in South America. The thorax and
abdomen have scales and hairs respectively, as in Pyretophorus, but
the abdomen has in addition prominent lateral apical scale tufts
to the segments and a scaly venter. Wings with membrane tinged in
patches and wing scales bluntly lanceolate and very dense. The
type is _A. maculipes_, Theob. found in Trinidad and Brazil; _A.
pseudomaculipes_, Cruz, also in Brazil.
Genus. *Myzorhynchus*, Blanchard; *Rossia*, Theobald.
_Compt. rend. heb. Soc. Biol._, 1902, No. 23, p. 795, Blanchard;
_Journ. Trop. Med._, 1902, p. 181, Theobald; “Mono. Culicid.,” 1903,
iii, p. 84; 1907, iv, p. 80; 1910, v, p. 49.
A very marked genus of large, dark, densely scaled species, found
in Europe, Asia, Africa and Australia. The thorax with hair-like
curved scales; the abdomen with ventral and apical scales, and a
median ventral apical tuft, and with very densely scaled palpi in
the female, and densely scaled proboscis. It seems to be mainly an
Asiatic and East Indian genus, but three species occur in Africa and
one in Australia. They are mostly sylvan species and bite severely.
Fourteen species are known. Five are malaria carriers (_vide_ list,
p. 566).
Genus. *Nyssorhynchus*, Blanchard; *Laverania*, Theobald.
“Mono. Culicid.,” 1910, iii, p. 14; v, p. 55, Theobald; _Compt. rend.
heb. Soc. Biol._, No. 23, p. 795, Blanchard.
A group of small, closely allied species found in Asia, Africa and
Australia, twelve out of the twenty species coming from India.
The thorax is covered with narrow curved and spindle-shaped scales,
abdomen with small, flat or narrow curved dorsal scales, especially
on the apical segments or in patches; the legs are always banded or
spotted with white, and the tarsi have as a rule one or more pure
white segments. (This banding and spotting is of no generic value,
however.)
The species show considerable seasonal variation. The type of the
genus is _N. maculatus_, Theobald.
Three are malaria carriers (_vide_ list, p. 566).
Genus. *Cellia*, Theobald.
“Mono. Culicid.,” 1903, iii, p. 107; 1910, v, p. 67.
Very marked Anophelines, with densely scaly abdomens, the scales
irregularly disposed on the dorsum and forming dense lateral tufts;
thorax with flat spindle-shaped scales; palpi densely scaled and also
the wings.
The type of the genus is the African _C. pharoensis_, Theob. It is
represented in Asia by _C. kochii_, Dönitz; in West Indies and South
America by _C. argyrotarsis_, Desvoidy, and _C. bigotii_, Theob.; in
Africa by _C. squamosa_, Theob., etc.
_C. argyrotarsis_, Desvoidy, and _C. albimana_, Wiedemann, are
undoubtedly malaria bearers.
Genus. *Neocellia*, Theobald.
“Mono. Culicid.,” 1907, iv, p. 111.
Allied to Cellia, but has no lateral scale tufts. Three species
recorded from India.
Genus. *Kertészia*, Theobald.
“Ann. Mus. Nat., Hung.,” 1905, iii, p. 66.
This genus has the thoracic scales hair-like, except a few narrow
curved ones in front; abdominal scales long, broad and irregular.
A single species, _K. boliviensis_, Theob. from Bolivia.
Genus. *Manguinhosia*, Cruz.
The thorax has narrow hair-like curved scales and some broad straight
scales; others spatulate on the sides. Abdomen with fine hairs,
except the last three segments which are scaly. Tufts of scales on
the hind femora. Wing scales lanceolate.
The type is _M. lutzi_, Cruz, from Brazil.
Genus. *Chagasia*, Cruz.
“Brazil-Medico,” 1906, xx, pp. 20, 199.
This genus can at once be told by the antennal segments having many
dense scaly tufts. Type, _C. fajardoi_, Lutz, from Brazil.
Genus. *Calvertina*, Ludlow.
_Canadian Entomologist_, 1909, xli, pp. 22, 234.
The antennæ in this genus have outstanding scales on the second
segment, more appressed ones on the first. At least one abdominal
segment with long, flat, more or less spatulate scales. Type, _C.
lineata_, Ludlow, from Philippine Islands.
Genus. *Birónella*, Theobald.
“Ann. Mus. Nat. Hung.,” 1905, iii, p. 69.
At once told by the first submarginal cell being very small. Type,
_B. gracilis_, Theob. from New Guinea.
Sub-family. *Megarhininæ.*
Three genera occur in this marked sub-family; they are the largest
of all mosquitoes, and are very brilliantly coloured, and many have
tail fans. They occur in North and South America, Asia, Africa, and
Australia. The long curved proboscis is very marked. They are usually
spoken of as elephant mosquitoes; some are vicious blood-suckers at
times.
The three genera tabulate as follows:--
α. Palpi long in both sexes.
β. Last segment of ♀ palp round or
blunt as if broken Genus _Megarhinus_, R. Desvoidy.
ββ. Last segment of ♀ palp long
and pointed Genus _Ankylorhynchus_, Lutz.
αα. Palpi of female short of male
long.
Palpi of female not more than
one-third length of proboscis Genus _Toxorhynchites_, Theobald.
Genus. *Megarhinus*, Robineau Desvoidy.
“Mém. Soc. d’Hist. nat. de Paris,” 1827, iii, p. 412; “Mono.
Culicid.,” 1901, i, p. 215; 1903, iv, p. 163; 1907, iv, p. 128; 1910,
v, p. 89.
All large brilliant mosquitoes with long palpi in both sexes and, as
a rule, with a caudal fan of scales; the proboscis is long and bent.
They are all sylvan species, and are not so far recorded as biting
man.
Genus. *Toxorhynchites*, Theobald.
“Mono. Culicid.,” 1901, i, p. 244; 1903, iii, p. 119; 1907, iv,
p. 140; 1910, v, p. 95.
Differs from the former genus in that the female palpi are short. The
palpi may have one, two or three minute terminal segments. Banks’s
genus Worcesteria has three.
The elephant mosquito of India (_T. immisericors_), Walker, bites
very severely. They are sylvan species.
Sub-family. *Culicinæ*.
Genus. *Mucidus*, Theobald.
“Mono. Culicid.,” 1901, i, p. 268; 1910, v, p. 125.
This genus is so far confined to Australia, West and Central
Africa, India, East Indies and Malay Peninsula. They are all large
mosquitoes, easily told by the whole body being more or less covered
with long twisted scales, giving them a mouldy appearance, and the
legs densely scaled with outstanding scales; the wings with large
parti-coloured scales. The Australian _M. alternans_, Walker, occurs
in larval form both in fresh and salt water. The adults bite man.
Genus. *Psorophora*, Robineau Desvoidy.
“Mém. de la Soc. d’Hist. nat. de Paris,” 1827, iii, p. 412, R.
Desvoidy; “Mono. Culicid.,” 1901, i, p. 259; 1903, iii, p. 130; 1907,
iv, p. 158; 1910, v, p. 123, Theobald.
This genus is confined to the Americas and the West Indies. Several
species exist which can easily be told from Mucidus by the absence
of long twisted scales and the narrower wing scales. The legs are
densely scaled and the thorax ornamented with flat spindle-shaped
scales.
_P. ciliata_, Robineau Desvoidy, occurs in both North and South
America, and bites man.
Genus. *Janthinosoma*, Arribalzaga.
“Dipt. Arg.,” 1891, p. 52, Arribalzaga; “Mono. Culicid.,” 1901, i,
p. 253; 1903, iii, p. 124; 1907, iv, p. 152; and 1910, v, p. 118,
Theobald.
Hind legs only densely scaled; some of the hind tarsi are always
white. The venation is as in Culex. The abdomen is metallic and
iridescent. They all bite man and occur only in the Americas and West
Indies.
Genus. *Stegomyia*, Theobald.
“Mono. Culicid.,” 1901, i, p. 283; 1903, iii, p. 130; 1907, iv,
p. 170; 1910, v, p. 151.
This, the most important genus in the _Culicinæ_, can be told by the
head and scutellum being clothed with flat scales and the thorax with
narrow curved ones.
About forty species are known in this genus, occurring in Southern
Europe, Asia, Africa, Australia, the Americas, East and West
Indies, and on most oceanic islands. Many of them seem to be
vicious blood-suckers. They are mostly black and white mosquitoes,
and several seem to go by the name of tiger mosquitoes. The genus
contains the yellow fever mosquito (_S. fasciata_, Fabricius), the
only one that need be dealt with in detail here. The chief known
species tabulate as follows:--
A. Proboscis banded.
α. Legs basally banded.
Thorax brown, with scattered creamy-
white scales _annulirostris_, Theobald.
Thorax black, with narrow, curved
golden scales _periskelta_, Giles.
αα. Legs with basal and apical banding.
Fore legs with no bands; mid with
apical and basal bands on first and
second tarsals, hind with basal bands.
Thorax white in front, with a brown
eye-like spot on each side _thomsoni_, Theobald.
AA. Proboscis unbanded.
β. Legs basally banded.
γ. Abdomen basally banded.
Thorax with one median silvery-white
line _scutellaris_, Walker.
Thorax as above, but pleuræ with white
lines _pseudoscutellaris_, Theobald.
Thorax similar, but two white spots
near where line ends _gelebinensis_, Theobald.
Thorax with two median yellow lines
and lateral curved silvery lines _fasciata_, Fabr.
Thorax with two short median lines and
a white patch on each side _nigeria_, Theobald.
Thorax with large lateral white spots
in front, smaller ones by wings, two
narrow median lines and two posterior
sub-median white lines _lilii_, Theobald.
Thorax with a white *W*-shaped area in
front, a prolongation curved on each
side enclosing a brown eye-like spot _W-alba_, Theobald.
Thorax with white frontal median spot,
two large lateral spots, a small one
in front of the wings, a narrow median
white line and narrow sub-median ones
on posterior half. _Last two hind
tarsi white_ _wellmannii_, Theobald.
Thorax brown, with broad white line in
front extending laterally towards
wings, where they swell into a large
patch, a white line on each side just
past wing roots. _Last two hind tarsi
white_ _albipes_, Theobald.
Thorax with silvery white spot on each
side in front, small one over roots of
wings and white over their base. _Last
two hind tarsi white_ _pseudonigeria_, Theobald.
Thorax with two lateral white spots,
front ones the largest, a small median
one near head, two yellow median
lines, a short silvery one on each
side before the scutellum _simpsoni_, Theobald.
Thorax with silvery-white scaled area
in front and another on each side in
front of wings _argenteomaculata_, Theobald.
Thorax with median yellowish-white
line, a silvery patch on each side in
front of wings extending as a fine
yellow line to the scutellum, and
another silvery spot before base of
each wing _poweri_, Theobald.
Thorax with small grey-scaled area in
front of wing roots and three short
creamy lines behind _minutissima_, Theobald.
Thorax (?) denuded; abdomen black;
fifth segment with yellow basal band;
sixth unbanded; seventh, two median
lateral white spots; eighth, two basal
lateral white spots; second hind
tarsal nearly all white _dubia_, Theobald.
γγ. Abdomen unbanded.
First hind tarsal all white, second
basally white, last two dark. Thorax
chestnut brown, with a broad patch of
white scales on each side in front and
a median pale line _terreus_, Walker.
ββ. Legs with white lines as well as basal
bands.
Thorax brown, with white lines; abdomen
with basal bands _grantii_, Theobald.
βββ. Fore and mid legs with apical bands,
hind basal.
Fourth tarsal of hind legs nearly all
white _mediopunctata_, Theobald.
Mid metatarsi with basal pale banding,
base and apex of hind, also base of
first tarsal pale _assamensis_, Theobald.
ββββ. Legs unbanded.
δ. Abdomen basally banded.
Thorax with front half white, rest
bronzy-brown _pseudonivea_, Ludlow.
Thorax deep brown, with scattered
golden scales, showing two dark eye-
like spots; head white, dark on each
side and behind _albocephala_, Theobald.
Thorax brown with golden stripes;
abdomen with narrow basal bands on
fifth and sixth segments only _auriostriata_, Banks.
δδ. Abdominal banding indistinct.
Thorax with broad silvery white patch
on each side in front _albolateralis_, Theobald.
δδδ. Abdomen unbanded.
Thorax with six silvery spots _argenteopunctata_, Theobald.
δδδδ. Abdomen with apical white lateral spots.
Thorax unadorned, except for pale
scaled lines laterally _punctolateralis_, Theobald.
δδδδδ. Abdomen with basal white lateral spots.
Thorax with two pale median parallel
lines and two silvery lateral spots _ininuta_, Theobald.
Thorax unadorned.
A white spot middle of head _tripunctata_, Theobald.
No white spot _amesii_, Ludlow.
AAA. Proboscis yellow basally, dark
apically. Abdomen with apical pale
bands _crassipes_, Van der Wulp.
AAAA. Proboscis with median interrupted white
line on basal half.
Head black, anterior margin grey _albomarginata_, Newstead.
*Stegomyia fasciata*, Fabricius (Yellow Fever Mosquito).
This insect, which is the proven carrier of yellow fever, is commonly
called the tiger, brindled, spotted day or striped mosquito. It
is also referred to by some writers as _S. calopus_, Meigen. It
is subject to considerable variation in colour, but the thoracic
markings are generally very constant. The general colour is almost
black to deep brown, the head with a median white area, white at
the sides and in front around the eyes; the thorax has two median
parallel yellow lines, a broad curved silvery one on each side and
white spots at the sides; the scales on the intervening spaces of the
thorax are brown. The dark abdomen has basal white bands and basal
white lateral spots. The dark legs have basal white bands, the last
segment of the hind legs being all white except in a variety from
South America and the West Indies (_luciensis_), which has the tip of
the last hind tarsal dark. The abdomen may also vary in colour, some
having pale scales over most of the surface (_queenslandensis_).
The food of the adult female consists mainly of man’s blood, but she
will also feed on dogs and other animals. The male has been said to
bite, but such is very unusual. This mosquito bites mainly in the
daytime up till about 5 p.m.
The adults breed the first day after emergence. They may live a
considerable time, Bancroft having kept females for two months in
confinement. The ova are laid separately, often in chains; they
are black, oval, with a reticulated membrane outside, some of the
reticulated cells containing air. They may hatch in from six to
twenty hours, the larval stage nine days, the pupal stage three; thus
the whole cycle may be completed in from twelve to thirteen days.
The ova when dry can remain undeveloped for a considerable time. The
larvæ are greyish-white, with short, thick siphon, and feed at the
bottom of the water, only coming to the surface now and again to
breathe. This is almost entirely a domesticated gnat, seldom being
found far from man’s habitations. Its larvæ occur in such small
collections of water as old sardine tins, jam-pots, calabashes,
puddles, barrels, wells--in fact, wherever water is held up, even to
the gutters of houses. Not only are they found breeding on land, but
also on board ship, although they prefer artificial collections of
water. They may also breed in larger natural collections.
This insect is easily transported by steam and sailing ships and by
train, and this doubtless explains its very wide distribution. The
adults may live for fifty days, and it is on this account and their
frequent occurrence on ships that danger lies in regard to the Panama
Canal. An infected insect may leave that endemic centre of yellow
fever and live until the vessel arrived at the Philippine Islands and
fly ashore, and so introduce the disease for the native _fasciata_
possibly to spread.
Roughly the distribution of this pest is as follows: Africa from
South to North, but especially along the coast and up the Nile. In
Asia, in India, Ceylon, Burma, Siam, along the ports of the Malay
Peninsula, in French Cochin China, Philippine Islands, the Andaman
and Nicobar Islands, Japan, Malay Archipelago, and East Indies,
Turkey in Asia, Arabia and Palestine.
In Australia it occurs in Queensland, New South Wales, Victoria and
South Australia.
In Europe in Italy, Spain, Portugal, Greece, in the Mediterranean
Islands.
In South America, Central America, Mexico, North America, and the
West Indies it is very abundant, and it also is found in the Bahama
Islands, Fiji, Sandwich Islands, Samoa, the Azores, Teneriffe and
Santa Cruz, Pitcairn Islands and Bermuda.
For a full account of its distribution the reader is referred to the
following: “The Distribution of the Yellow Fever Mosquito (_Stegomyia
fasciata_, Fabricius) and General Notes on its Bionomics;” “Mém.
1^{er} Congrès international d’Entomologie, 1911, ii, pp. 145–170,
F. V. Theobald.” In addition to being the yellow fever carrier, it
is supposed by Wenyon to be the intermediate host of the parasite of
Bagdad sore.
*Stegomyia scutellaris*, Walker.
A vicious biter, found in India, China, Malay, East Indies, and
Ceylon. The thorax has one median silvery stripe, and so can easily
be told from _S. fasciata_.
A very similar species occurs in Fiji, but can be told by the pleuræ
having white lines, not spots (_S. pseudoscutellaris_, Theobald). It
is the intermediate host of filaria in Fiji (Bahr).
A number of nearly allied genera occur here (_vide_ synoptic table).
Genus. *Theobaldia*, Neveu-Lemaire.
*Theobaldinella*, Blanchard.
Includes several large Culicines, of which _T. annulata_, Meigen,
is the type. The wings are usually spotted (_annulata_, _incidens_,
etc.), but may be nearly plain (_spathipalpis_). The males have the
palpi swollen apically, and the females have long five-jointed palps.
Several of these are vicious biters.
*Theobaldia annulata*, Meigen.
This large gnat (6 mm. long) can be told by its wings having five
large spots of dark scales and by its legs having broad basal white
bands to the tarsi. The larvæ occur in rain barrels and small pools.
It is essentially a domestic form, occurring in houses and privies.
Its distribution is Europe generally and North America. The bite is
very severe, and in some districts gives rise to painful œdema.[392]
[392] Theobald, “Second Report on Economic Zoology,” 1903, p. 9.
_Theobaldia spathipalpis_, Rondani, occurs in Italy, Mediterranean
Islands, Palestine, the Himalayas, Khartoum, and in South Africa. It
is about the same size as _T. annulata_, but is yellowish-brown in
colour, with striped thorax and mottled and banded legs. It occurs in
privies and bites very severely.
Genus. *Culex*, Linnæus.
“Syst. Nat. Ed.,” 1758, x, Linnæus; “Mono. Culicid.,” 1901, i,
p. 326; 1910, v, p. 322, Theobald.
This large genus still contains many forms which should be excluded.
The species normally have narrow curved median head-scales, and
similar ones on the scutellum; the female palpi are shorter than
in the former genus and the male palpi are pointed; the lateral
vein-scales are narrow and linear.
[Illustration: FIG. 400.--Wing of a Culex.]
The type is _Culex pipiens_, Linn., the common gnat of Europe.
The thorax is covered with narrow curved golden-brown scales,
the abdomen has basal pale bands to the segments and the legs and
proboscis are unbanded. The stem of the first submarginal cell is
always less than one-fifth the length of the cell. It lays its eggs
in rafts in water-butts, etc., and even in the foulest water. They
are first deposited in England in June and July, and again soon after
hatching in August. In some districts this gnat bites man viciously,
in others not at all.
The common tropical gnat (_Culex fatigans_, Wied). This resembles the
European _Culex pipiens_, but can always be told by the stem of the
first submarginal cell always being much longer than it is in _C.
pipiens_. This is one of the species that has been proved to transmit
filariæ to man, etc. Varieties of it occur in almost every country
between 40° N. and S., having a very similar range to _S. fasciata_.
In all countries it appears to be connected with the transmission of
_Filaria bancrofti_, and it is also said to carry the micrococcus of
dengue fever.
Genus. *Melanoconion*, Theobald.
“Mono. Culicid.,” 1903, iii, p. 238; 1907, iv, p. 507; 1910, v,
p. 455.
This genus is composed of eight species, most of which are small
black gnats which bite viciously and which occur in swamps and
jungles. They can at once be told from Culex by the veins of the
wings having dense broadened scales on their apical areas and along
the upper costal border. The femora and apices of the tibiæ are
swollen.
The black mosquito, _Melanoconion atratus_, Theob. This small
gnat is a very troublesome pest in swamps in the West Indies. The
female bites both by day and by night, and the bite causes severe
irritation. The larvæ live in permanent ponds. It is almost black in
colour, but sometimes presents a dull coppery sheen; each segment has
small lateral basal white spots. Length 2·5 to 3 mm.
It occurs in Para and British Guiana as well as in the West Indies.
Ordinary mosquito netting is no use for keeping off this pest.
Genus. *Grabhamia*, Theobald.
“Mono. Culicid.,” 1903, iii, p. 243; 1907, iv, p. 284; and 1910, v,
p. 277.
Allied to Culex, but separated by the wings having short fork-cells,
mottled scales, the median ones thick and also some of the lateral
ones short and broad; the last two joints of the male palps are very
slightly swollen. The eggs are laid singly, not in rafts, and the
larvæ have short, thick siphons. Ten species occur and are found in
Europe, North America, West Indies and Natal. _G. dorsalis_, Meigen,
bites severely in Europe. _G. sollicitans_, Walker, is a great
scourge along the New Jersey Coast and at Virginia summer resorts
and in Florida. It breeds in brackish water and is the most common
mosquito of the Atlantic seaboard.
Genus. *Pseudotæniorhynchus*, Theobald; *Tæniorhynchus*, Theobald,
non-Arribalzaga.
Differs from the former in having the whole wing veins clothed with
dense, broadish elongated scales. They occur in South America (_T.
fasciolatus_, Arri.), in Africa (_T. tenax_, Theob.), in Europe (_T.
richardii_, Ficalbi). The latter bites very severely.
Genus. *Tæniorhynchus*, Arribalzaga; *Mansonia*, Blanchard;
*Panoplites*, Theobald.
_Compt. rend. heb. Soc. Biol._, 1901, iii, 37, p. 1046; “Mono.
Culicid.,” 1901, ii, p. 173; and 1910, v, p. 446, Theobald.
A very marked genus, easily told by the broad asymmetrical wing
scales. It occurs in Africa (_T. africana_ and _T. major_, Theob.);
in Asia (_T. uniformis_, Theob.; _T. annulipes_, Walker, etc.) and in
Australia (_T. australiensis_); in the Americas and West Indies (_T.
titillans_, Walker). The eggs (fig. 395, _d_) are peculiar in form
and are laid separately; the larva has not been described; the pupa
has long curved siphons. They mostly occur along rivers, in swamps
and forests, and bite very severely. They also enter houses (_T.
titillans_). _T. uniformis_ is most troublesome during the rains.
The saliva is strongly acid. Both these species carry the larvæ of
_Filaria bancrofti_.
Genus. *Chrysoconops*, Goeldi.
“Os Mosq. no Para,” 1905, p. 114, Goeldi; “Mono. Culicid.,” 1910, v,
p. 433, Theobald.
Bright yellow or yellow and purple mosquitoes, with rather dense wing
scales. Numerous species occur in Africa (_aurites_, _annettii_,
_fuscopennatus_, etc.), others in India, Australia and South America.
Low found filariæ in the thoracic muscles of _fuscopennatus_ in
Uganda.
Several of the _Ædeomyina_ bite, especially the small _Uranotænias_.
They are all sylvan species, seldom entering houses. They need not,
therefore, be referred to here.
For full details of the Culicid genera and species the reader is
referred to my monograph[393] and other works mentioned below.
[393] “A Monograph of the _Culicidæ_ of the World,” 5 vols. and atlas,
1901 to 1910, British Museum (Nat. Hist.); and the following: Howard,
Dyar and Knab, “The Mosquitoes of North and Central America and the
West Indies,” 1912; James and Liston, “The Anophelinæ of India,”
Leicester, 1908; “The _Culicidæ_ of Malay,” Inst. Med. Res., Fed. Malay
States, iii; _Ann.Trop. Med. and Par._, papers by Newstead and Carter;
_Mem. Inst. Oswaldo Cruz_, papers by Lutz, Neva, Chagas; and the
_Bulletin of Entomological Research_, etc.
Other Nematocera.
Other nematocerous flies are midges, daddy-long-legs and sand-flies.
The ones which cause annoyance to man besides _Culicidæ_ are the
following:--
Sand-flies (_Simulidæ_), certain midges (_Chironomidæ_), and a few
owl midges (_Psychodidæ_).
The _Nematocera_ have long thread-like jointed antennæ and their pupæ
are, as a rule, naked; the larvæ have a distinct head and can thus be
told from the next section (_Brachycera_).
Family. *Simulidæ.*
This family consists of a single genus, Simulium, Latreille, which
Roubaud has recently divided into two sub-genera called Pro-Simulium
and Eu-Simulium. These insects, which are frequently spoken of as
sand-flies, are found in all parts of the world; they are all small
insects varying from 1·5 to 3 mm. The females are very bloodthirsty,
but the males appear to be incapable of sucking blood.
The head sunk under the humped thorax; antennæ short, straight;
palpi short and broad, of four segments, bent; wings broad and in
some iridescent, legs stout. The male has holoptic eyes, whilst in
the female they are small and widely separate. The sucking proboscis
is short. The thorax and abdomen are clothed with short hairs which
may form spots and markings; these are golden, silvery, grey, or
brownish. In the sub-genus Pro-Simulium the second segment of the
hind tarsi in both sexes is elongate, linear, and without a basal
notch; in Eu-Simulium it is short, curved, and dorsally notched at
the base.
_Simulidæ_ often occur in swarms, and attack not only man but cattle,
horses, and poultry. In some districts they are more annoying than
mosquitoes.
Their life-cycle has been most completely worked out by King, in
Africa.
The larvæ and pupæ occur in swiftly flowing water, by waterfalls, in
rapids, etc. The ova are laid in gelatinous masses on plants or rocks
close to or overhanging the water. The larva is cylindrical, enlarged
posteriorly, where it is provided with a sucker, by means of which it
attaches itself to a rock, water weeds, debris, etc.; anteriorly it
has a proleg close behind the head on the lower surface. The head is
dark and chitinous. The respiration takes place by means of branched
tracheal gills which protrude from the dorsal surface of the last
body segment; they are retractile. The colour varies from deep green
to yellow or almost black. Their food consists of algæ and other
organisms in the water brought to their mouth by two fan-like organs
placed on the head. The larvæ can crawl from place to place by means
of the thoracic proleg; they occur in masses, usually in a more or
less erect attitude. A network of threads is spun on their support,
by means of which King tells us “they are enabled to maintain their
position against the strongest current; frequently they will leave
their support and let themselves out into the stream anchored by
threads of silk and enabled by them to return.”
When full fed the larva spins a pocket-shaped cocoon on the support,
within which it pupates. The pupa is motionless and has a pair of
branched spiracles projecting from behind the head. When the adult
emerges, a bubble of air collects around it, and in this it floats to
the surface and at once takes wing. The European species take a month
to complete larval life, a week being spent in the pupal stage. The
flies are most restless, and even when stationary continually move
their legs about like feelers. Sometimes the swarms consist entirely
of females, sometimes early in the season mostly of males.
The females pierce the skin of humans on tender spots, such as ears,
the forehead, around the eyes and nose, and crawl into the cavities.
They are quite harmless at night, mainly attacking about sunrise and
sunset. Some crawl up the arms and legs and down the neck, and leave
behind little red weals which itch intensely (_S. damnosum_, Theob.),
and blood may flow freely from the wounds.
The following are some of the worst species:--
_Simulium columbaschensis_, the “Kolumbatz fly,” which abounds in the
damp marshy lands along the Danube, and is a great plague to man and
beasts in Hungary, and is also abundant in Austria and Moravia, and
is most numerous after inundations from the Danube. They sometimes
appear in such swarms that it is impossible to breathe without
getting them into one’s mouth. There are instances of children being
killed by these flies when left on the ground by their mothers when
working in the fields.
_S. damnosum_, Theob. This occurs throughout Equatorial Africa and is
known as the “jinja fly” in Uganda, the “fouron” in the French Congo,
the “kilteb” in the Sudan. It is a most vicious biter, and in some
parts occurs in “belts”; Dr. Christy found one such extending from
the shores of the Victoria Nyanza northwards along the right bank of
the Nile for twelve or fifteen miles or more, and perhaps three or
four miles wide. In this area the flies swarm in millions at certain
seasons, so much so that the natives have to leave their plantations.
The bite causes a weal, marked by a drop of blood.
_S. griseicollis_, Becker. The so-called “nimitti” occurs in Upper
Egypt and the Anglo-Egyptian Sudan. It lives near the river and is
not found more than half a mile from it. Human beings are bitten on
the face and hands, animals in the region of the pudenda.
_S. latipes_, Meigen. This is a European species, also found in Natal.
_S. wellmanni_, Roubaud. The “ohomono” of Angola, where it bites
viciously and is dreaded by the naked porters.
_S. buissoni_, Roubaud. Occurs in abundance in the Marquesas Islands.
It has been _suggested_ that this species may help to propagate
leprosy.[394]
[394] _Bull. du Mus. d’Hist. nat._, 1906, xii, p. 522.
A large number of these insects have been described by Lutz in
Brazil.[395]
[395] _Mem. Inst. Oswaldo Cruz_, 1910, ii, fasc. 2, pp. 211–267.
A _Simulium_ sp. (?) is very harmful to poultry in Cape Colony.[396]
[396] C. Fuller, “A New Poultry Pest,” 1899, Leaflet No. 1, Dept. Agric.
In America, _Simulidæ_ are most annoying. One, _S. meridionale_,
Riley, also known as the turkey gnat in the Mississippi Valley, has
been supposed to be the carrier of chicken cholera; anyhow, it has
caused the death of thousands of chickens and turkeys in Virginia
annually.[397]
[397] _Insect Life_, 1888, i, p. 14.
In Mexico Townsend found a Simulium which was named _S.
occidentalis_, which caused great annoyance to man, many people being
so susceptible to them as to preserve through the gnat season a
chronic inflammation of the exposed parts of face and neck, resulting
from the repeated bites giving rise to sores.[398]
[398] _Ibid._, 1893, v, p. 61.
Men and horses have been partially incapacitated by the bites of
sand-flies or Simulium in a Hampshire wood (Cantlie, _Brit. Med.
Journ._, April 28, 1900, v, No. 2,052, p. 1023).
[Illustration: FIG. 401.--Wing of Simulium.]
[Illustration: FIG. 402.--Wing of Chironomus.]
Family. *Chironomidæ* (Midges).
The _Chironomidæ_ or midges are not only frequently mistaken for
mosquitoes, but some are very annoying to man by biting him as
mosquitoes do. They are easily distinguished from true mosquitoes
(_Culicidæ_) by the following characters: (1) head small, often
retracted under the cowl-like thorax; (2) no scales to the wings
or body; and (3) the different arrangement of veins on the wings
(fig. 402).
Two genera are important as annoying man, namely, Culicoides,
Latreille, and Johannseniella, Williston. The larvæ of _Chironomidæ_
are either aquatic, both fresh water and marine, and help to
make the former foul,[399] according to Slater, or may, as in
_Ceratopogoninæ_, live beneath the bark of trees, etc. The pupæ
are very varied and also the life-histories of the different
genera.[400] The blood-sucking habit is confined to the sub-family
_Ceratopogoninæ_.
[399] _Entomologist_, 1879, p. 89.
[400] Theobald, “An Account of British Flies,” i, p. 172.
Sub-family. *Ceratopogoninæ.*
This sub-family of midges consists of very small species varying from
1 to 2 mm. in length; the wings have darkened areas, and the second
longitudinal vein is wanting, and the first and third veins are
stouter than the others and placed close to the anterior margin, the
fourth and fifth are forked; the antennæ in both male and female are
composed of fourteen segments, six or eight in the males bearing long
hairs.
The chief blood-sucking species belong to the genera Culicoides,
Latreille, and Johannseniella, Williston. The latter genus differs
from the former in the absence of an empodium or median appendage on
the last segment of the tarsi. The genus Ceratopogon, as restricted
by Kieffer, is not supposed to take vertebrate blood, but Austen has
recently noticed that the type specimen of _C. castaneus_, Walker,
and a new species described by him, apparently have their bodies
distended with blood. The wings in the _Ceratopogoninæ_ are carried
flat when at rest.
[Illustration: FIG. 403.--A Ceratopogon, or midge. Greatly enlarged.]
In spite of their small size the females are the most bloodthirsty
and annoying of all insects. The Culicoides, which are often called
“sand-flies,” bite during the day and rarely at night. Usually they
are most troublesome between 3 and 6 p.m. They frequently attack in
swarms, especially in the open, and owing to their minute size can
get through fine mosquito netting. Some of them produce a distinct
“buzz” when on the wing. These insects are found in all parts of the
world. No species has been definitely connected with any disease, but
Culicoides has been suspected of carrying the germs of Delhi boil.
The larvæ of Culicoides are elongate in form and have smooth bodies
composed of thirteen segments including the head, which is horny;
there is no proleg on the first segment as seen in Chironomus, and on
the anal segment are retractile gills. They are very active and live
in the sap of various trees which saturates diseased bark.
The pupæ are smooth, but the abdominal segments bear a transverse
row of small spines. Austen describes a number of Culicoides and one
Johannseniella and three Ceratopogons from Africa,[401] and Lutz[402]
a number of this sub-family from Brazil, including a new genus,
Centrorhyncus. Another genus, Tersesthes, Townsend (Centrotypus,
Grassi; Mycterotypus, Noe), also occurs in Brazil.
[401] _Bull. Ent. Res._, 1912, iii, pp. 99–108.
[402] _Mem. Inst. Oswaldo Cruz_, 1913, v, fasc. 1, pp. 45–72, pls. 6–8;
and 1914, vi, fasc. 2, pp. 81–99.
_Culicoides ornatus_, Taylor, is described from Townsville,
Australia, found in mangrove swamps. It is a very vicious biter and
causes considerable irritation, settling on hands and wrists (Taylor,
_Rep. Ent. Aust. Inst. Trop. Med._ (1912), 1913, p. 24).
Family. *Psychodidæ* (Owl Midges).
This family of diptera is of considerable importance, not only on
account of the blood-sucking habits of some species, but especially
on account of one at least having been proved to be the carrying
agent of “papataci” fever, a three-day fever very prevalent in Malta
and several parts of Southern Europe in the autumn.
It is also possible that these small flies are connected with the
formation of “Delhi boil,” caused by a protozoan parasite.
[Illustration: FIG. 404.--An owl midge, _Phlebotomus_ sp. Greatly
enlarged. (From Giles’s “Gnats or Mosquitoes.”)]
_Psychodidæ_ are all very small flies, many of which have a moth-like
appearance, and owing to their fluffy nature are spoken of in
Britain as “owl flies,” sometimes also as “window flies.” Their
bodies and wings are covered with hairs, densely in some (sub-family
_Psychodinæ_), and in a few with patches of flat squamæ. In the
non-blood-sucking _Psychodinæ_ the wings are carried in a peculiar
manner downwards over the body, to a _slight extent_ resembling the
_Hepialidæ_, or swift moths. The wings may be ovoid or lanceolate,
and have a marked venation as seen in the figure. The proboscis
is short and non-suctorial in the majority of genera, but in the
sub-family _Phlebotominæ_ it is elongated and hard. The antennæ are
long and of sixteen segments, and bear whorls of fine hair.
There are two sub-families, _Psychodinæ_ and _Phlebotominæ_; in the
former the mouth is not suctorial; the female has a horny ovipositor
and the second longitudinal vein is branched at the root of the wing;
in the second sub-family the proboscis may be formed for sucking,
the female has no horny ovipositor, and the second long vein has its
first fork near the middle of the wing.
The sub-family _Phlebotominæ_ contains the genus Phlebotomus, which
occurs in South Europe, South Asia, Africa, North and South tropical
America. They are all small grey, brown, or dull yellow-coloured
flies, and carry their wings when at rest upwards like a butterfly.
The proboscis is moderately long and the legs long and thin.
The females are most vicious blood-suckers, but in some species
anyhow the males also bite (_P. duboscii_). They are mainly
nocturnal feeders and hide away during the day in any dark corners or
crevices.
The life-cycle has been worked out by Newstead[403] and Grassi[404]
in Europe, and by Howlett[405] in India.
[403] _Bull. Ent. Res._, 1911, ii, pt. 2, pp. 47–78.
[404] “Ricerche sui Flebotomi,” _Mem. della Soc. ital. della Scienze_,
1907, ser. 3, xiv, pp. 353–394.
[405] “Indian Sand-flies,” _Ind. Med. Cong._, 1909, sec. III,
pp. 239–242.
The larvæ have been found in crevices in rocks and caves, in dirty
cellars, and dark damp places containing rubbish, and are also said
to live in crevices in the walls of privies and cesspits.
The minute larva is very marked; as figured by Newstead it has two
long chætæ projecting upwards, in some stages branched, in others
simple, and on the segments a few blunt spine-like processes. The
pupæ are found in similar situations. The ova are very minute,
elongate, translucent white, and covered with a thin coating of
viscous matter when first laid; soon after they become dark brown,
shiny, with long black wavy lines. Newstead found the incubation
period in Malta to last for about nine days in _P. papatacii_. Five
species are known in Europe, five in Africa,[406] two in North
America, and eight are described by Annandale[407] in the Oriental
region. Lutz and Neiva have described three species from Brazil[408]
(_P. longipalpis_, _intermedius_ and _squamiventris_).
[406] Newstead: _Bull. Ent. Res._, 1912, iii, pp. 361–367.
[407] _Rec. Ind. Mus._, v, pt. 3, Nos. 13 and 14.
[408] _Mem. Inst. Oswaldo Cruz_, 1912, iv, fasc. I, pp. 84–95.
*Brachycera* (Flies).
The antennæ as a rule have three segments, and are usually shorter
than the head. The first segment of the antennæ is frequently very
small, and the third one is generally the largest, and sometimes
possesses a terminal annulated bristle. The palpi have from one to
three segments; the mandibles are covered by the labium. The three
thoracic rings are coalesced; wings are almost always present, the
posterior ones being rudimentary and covered with a little scale.
From the ova legless maggots are hatched, which as a rule have not a
distinct head, but occasionally possess two claw-like hooklets. These
maggots live in decomposing organic matter; they rarely live in water
and some of them are parasitic. They either become barrel-shaped
pupæ within the last larval integument or, after casting it, are
transformed into naked pupæ. The larvæ of numerous _Brachycera_
have been observed in man, some in ulcers or on mucous membranes,
others in the skin or in the intestine, etc. In many cases the report
only mentions the presence of the larvæ of flies; in other cases
the species has been determined; whilst in still other cases the
corresponding adult creature is unknown. We must therefore confine
ourselves to describing the most common varieties.
Family. *Phoridæ.*
These flies belong to the same division of _Diptera_, the Aschiza, as
the family _Syrphidæ_ or “hover flies.” They are all small insects
with marked antennæ and wings; the former have the third segment
globular and enlarged, and thus hiding the first two; the wings are
short and broad, the venation shows two short, thick, long veins with
four thin ones running out from them. The larvæ normally live in
decaying animal and vegetable matter, but one species, _Aphiochæta
ferruginea_, Brun., has been found as an intestinal parasite of man.
*Aphiochæta ferruginea*, Brun.
This small fly belonging to this family is of an orange-ochreous
colour, the upper part of the thorax tawny, and with dark bands on
the abdomen, legs pale yellow, the hind femora tipped with dark
brown. It measures only 2 to 3 mm. in length. This insect is shown by
Austen to be widely distributed in the tropics, being found in India,
Burma, West Africa, and Central America. The larvæ breed in decaying
animal matter, such as putrid meat, decomposing shell-fish, etc.
Heusner bred out sixty-three flies from larvæ taken from an Indian’s
foot.
Baker (_Proc. Burma Branch Brit. Med. Assoc._, 1891, p. 11–16) found
that the maggots of this fly were passed _per anum_ by a European at
intervals during a period of ten months. Baker found that the larvæ
fed on human fæces; from the egg stage to the deposition of eggs from
the resultant brood of flies occupied twenty-two days. He concludes
that they are capable of propagating, and do so while living within
the human intestines. He also records the larvæ in two girls.
The larva does not seem to have been described, but Austen describes
the pupa (_Trans. Soc. Trop. Med. and Hyg._, iii, No. 5, p. 229).
*Phora rufipes*, Meig.
The larvæ of the “hump-backed fly” live in rotting potatoes,
mushrooms, radishes, etc., and when accidentally introduced into the
intestine of man can, like other larvæ, live there twenty-four hours
and even more, and may set up serious gastric disturbances.
_P. rufipes_ is the same as _P. pallipes_, Latr.
Family. *Sepsidæ.*
Small blackish flies, elongate, with abdomen narrowed at the base,
thickened and curved downwards towards the extremity. Larvæ often
found in decaying vegetables, ham, cheese, etc. The larvae have the
power of skipping; conical in form, pointed in front, truncated
behind, about 5 mm. long, shiny and smooth, the anal segment with
fleshy protuberances. The genus Piophila has a short proboscis and
the cross-veins of the wings approximate.
*Piophila casei*, L.
Cheese flies. The larvæ live in ripe cheese, with which they are
sometimes introduced into human beings (Meschede).
The larvæ of the cheese flies (_Piophila casei_) may pass through the
alimentary canal of human beings alive, and have been occasionally
referred to in cases of internal myiasis. It also breeds in dead
bodies in adipose tissue. Howard records it on human excrement. It
is thus possible that some of the recorded cases of this pest being
passed alive may be due to eggs deposited on human fæces.
Family. *Syrphidæ* (Hover and Drone Flies).
Amongst the large family of _Syrphidæ_ is found a section known as
the _Eristalinæ_ or drone flies, whose curious long-tailed larvæ
are popularly called “rat-tail larvæ,” on account of the end of the
body being drawn out into a long telescopic tail of two segments,
at the end of which are placed the breathing pores. These larvæ
live in water, no matter how foul, and in liquid manure. They have
occasionally been obtained in foul drinking water by human beings
and from eating watercress improperly washed or from badly kept
beds. Austen (_Trans. Soc. Trop. Med. and Hyg._, iii, No. 6, p. 221)
records that in the autumn of 1907 a number of the larvæ of the
common drone fly (_Eristalis tenax_) were passed _per rectum_ by a
woman in Hampshire who had recently arrived from France. The patient
had eaten a considerable quantity of watercress before leaving
France. I have twice found small Eristalis larvæ clinging by their
long tails on watercress served at table.
Family. *Drosophilidæ.*
Small, rather plump flies, with short, broad abdomen, with bristles
on the head and legs. Often abundant in decomposing fruit, and may
occur in dense masses.
*Drosophila melanogaster*, Br.
The larvæ of this fly occur in over-ripe fruit and in fungi, often
also in human habitations, and live in substances undergoing acid
fermentation (vinegar, decaying fungi, rotting fruit, in damaged
spots in diseased trees), much more rarely in animal substances, and
they occasionally gain access to the human intestine (for example, by
the medium of sour milk). When introduced in any quantity, they cause
vomiting or attacks resembling colic; when taken in the pupal stage
no unpleasant results are produced.
Family. *Muscidæ.*
*Teichomyza fusca*, Macq.
Syn.: _Scatella urinaria_, Rob. Desv.; _Ephydra longipennis_, Meigen.
The larvæ live in the urine in privies. Several authors state they
have found them in fresh fæces or in vomited matter. Pruvot states
that they continue for three days in the stomach of rats into which
they have been intentionally introduced. (Pruvot, G., “Contrib. à
l’étude des larves de dipt, trouv. dans le corps humain,” _Thèse de
Par._, 1882; Chatin, J., in _Comp. rend. Soc. de Biol._, Paris, 1888
(8), v, p. 396; Roger, H., _ibid._, 1851 (1), iii, pp. 88, etc.)
*Homalomyia canicularis*, L., etc.
_Homalomyia manicata_, Meig., live as larvæ in decomposing vegetable
matter or in cultivated vegetables (cabbage); they are easily
recognizable by their plumed bristles, which are situated laterally
on the body segments. They obtain access fairly often to the human
intestine and give rise to very uncomfortable symptoms. Cases have
been recorded from Germany, Austria, France, England, North America
(Wacker, in _Artzl. Intelligenzbl._, 1883, xxx, p. 109; Florentin,
in _Compt. rend. Soc. de Biol._, Paris, 1904, lvi, p. 525; and other
authors).
The larvæ of an allied genus (Anthomyia), which, however, does not
possess plumed bristles, has been found in the external auditory
meatus of a man (_A. pluvialis_, according to Danthon).
[_H. canicularis_ is common to Europe and North America, and is
an abundant house-fly. It is the small house-fly so often seen
on windows. Besides living on vegetable matter, they have also
been found in the nests of the humble bee. Larvæ of this species
(fig. 405) were sent to the British Museum, taken from the fæces of
a woman suffering from cancer.[409] They were found at Shrewsbury.
Hagen[410] reports the larvæ of this fly as occurring alive in the
urethra of a patient.--F. V. T.]
[409] Theobald, “First Report Economic Zoology,” _Brit. Mus. (Nat.
Hist.)_, p. 55.
[410] Hagen, _Proc. Bost. Soc., N.H._, xx, p. 107.
*Homalomyia scalaris*, Fabr.
[This is not a synonym of the above, but a distinct species.
[_H. manicata_, Meigen, is also distinct.--F. V. T.]
*Anthomyia desjardensii*, Macq.
This fly, allied to Homalomyia, is the cause of both intestinal and
cutaneous myiasis at Bihé, Angola (Wellman, _Journ. Trop. Med. and
Hyg._, June, 1907, x, p. 186).
*Hydrotæa meteorica*, L.
The larvæ live in decaying vegetable substances, also in dung, and
have been evacuated in some cases by man (Zetterstedt, Joseph).
[Illustration: FIG. 405.--Larva of _Homalomyia canicularis_. Enlarged.]
[Illustration: FIG. 406.--Larvæ of _Calliphora vomitoria_. Enlarged.]
[Illustration: FIG. 407.--Larva of _Chrysomyia macellaria_. 4/1. (After
Conil.)]
*Cyrtoneura stabulans.*
Larvæ in fungi, but occasionally also on larvæ of butterflies and
_Hymenoptera_; occasionally introduced into the human intestine
(Joseph).
*Musca domestica*, L.,
and _M._ (_Calliphora_) _vomitoria_, L., and allied species; larvæ
of these have been repeatedly found in the intestine and nose of man
(Mankiewicz, etc.).[411]
[411] “Larvæ of a Musca, probably _M. corvina_, were passed in numbers
_per rectum_ by a child in Liverpool with Homalomyia larvæ,”--“Second
Report Economic Zoology,” Theobald, 1903, p. 16.
*Musca domestica*, Linn. (Common House-fly).
It is not only on account of a few larvæ of the common house-fly
(_Musca domestica_) being found in the intestines of man that it is
of importance medically. It is far more important on account of the
part it plays in the spread of diseases of the intestines, such as
typhoid fever and cholera, infantile diarrhœa and dysentery.
Howard and Clark (_Journ. Exp. Med._, 1912, xvi, No. 6, pp. 850–859)
have shown that the house-fly is capable of carrying the virus of
poliomyelitis for several days on the surface of the body and for
several hours in the gastro-intestinal tract. The house-fly may also
distribute the ova of _Tænia solium_ and the white worms (Oxyuris and
Ascaris). It has also been proved that they may carry the germs of
tuberculosis, and it is said that they play an important part in the
spread of infectious ophthalmia in Egypt.
This insect is found in all parts of the world. In warm countries
it breeds all the year round, and it may do so even in temperate
climates in warm places, such as stove houses. Most, however, die
off in the autumn; but some survive the winter as adults, in such
places as kitchens, restaurants, and warm houses. I have never failed
to find a few _Musca domestica_ in houses during the winter. The
majority, however, hibernate as puparia.
The females deposit from 120 to 150 eggs in a batch in stable
manure, rotting vegetation, house refuse, spent hops, old soiled
bedding, etc. A single female may lay as many as six batches of ova
during her life. The eggs are shiny white, and hatch in from eight
to twenty-four hours in warm weather to three or four days in cool
weather. The white footless maggots are cylindrical, tapering to a
point at the head end, truncated posteriorly. The head consists of
two dark mandibular hooks and two short antennæ. On the tail end are
two plates, the stigmata, in which the main tracheal trunks open;
in the second segment are a small pair of projecting stigmata. The
larval stage lasts from seven to five days in hot weather; but in
cold weather in temperate climes it may last six or eight weeks.
The larva on reaching maturity becomes a barrel-shaped puparium of
a dark brown to black colour, and in this case changes to the pupa.
This stage lasts from three days in the tropics to four or five weeks
in cold weather, the life cycle thus varying from ten days in the
tropics to fourteen in warm weather in Europe up to three or four
months under unfavourable conditions.
All breeding grounds should be burnt or otherwise done away with,
such as stable manure, house and kitchen refuse, human excrement and
soiled substances, also decaying vegetation as soon as possible,
certainly by every sixth day. Stable manure should be kept in closed
receptacles and should be removed by every sixth day to at least
one mile from habitations and sprinkled with chloride of lime. All
kitchen and household refuse should be burnt at once or buried in
pits and covered with soil. Latrines should be as far as possible
from hospitals, mess rooms and tents. Food--especially milk, sugar
and fruit--should be kept screened with muslin when house-flies
are about. Mess rooms and tents and hospitals should have doors
and windows screened with fine wire gauze during the fly season.
All possible steps should be taken to prevent them contaminating
man’s food and from breeding in human excrement and from entering
hospitals. When present in dwelling-houses in numbers they may be
killed by fumigation with pyrethrum or sulphur.
Genus. *Chrysomyia*, Rob. Desv.
*Chrysomyia* (*Compsomyia*) *macellaria*, Fabr.; *Lucilia macellaria*,
Fabr.
Syn.: _Lucilia hominivorax_, Coq.; _Calliphora infesta_, Phil.;
_Calliphora anthropophaga_, Conil.
A species distributed from the Argentine to the south of the United
States which deposits its ova on ulcers, in the aural meatus or in
the nasal cavities of persons who sleep in the open air. The larvæ
are yellowish white, 16 mm. long, are armed with two strong mouth
hooks, and provided with spinous rings (screw-worm); they lie hid in
the nasal and frontal sinuses, in the pharynx, larynx, etc.; they
perforate the mucous membranes, even cartilage, migrate into the
eyes, the cranial cavity, middle ear, and cause severe disturbances;
after the mature stage, in which the larvæ leave the host to enter
the pupal state, these symptoms often spontaneously abate after a
lapse of eight days, leaving behind greater or less cicatrices, and
consequently also defects in function of the organs attacked. Very
often, however, sepsis sets in, usually with a fatal termination.
(Coquerel in: _Arch. gén. de méd._, 1858 (5), p. 513; 1859, xiii,
p. 685; _Ann. Soc. ent. France_, 1858 (3), vi, p. 171; 1859, vii,
p. 234. Weber in: _Rec. de mém. de méd. milit._, 1867 (3), xviii,
p. 159. Francius, A., in: _Arch. f. path. Anat._, 1868, xliii, p. 98.
Conil in: _Bol. Acad. nac. cienc. Cordoba_, 1881, iii, p. 296.
Humbert, Fr., in: _Proc. U.S. Nat. Mus._, 1883, vi, p. 103; _Amer.
Nat._, 1884, xviii, p. 540. Lindsay in: _Journ. Trop. Med._, 1902; v,
p. 220, and other authors.)
[Illustration: FIG. 408.--The screw-worm fly (_Chrysomyia macellaria_).]
[This species is known as the screw-worm fly. It attacks animals as
well as man, especially laying its eggs on wounds formed by barbed
wire. It may also be found on dead flesh. Dr. St. George Gray sent
me specimens from St. Lucia, from the nose and mouth of a patient
in Victoria Hospital. Others were found in the vagina of another
patient. Out of the four patients attacked, two occupied the same
bed, one after the other, and a third the next bed to it. The other
case was in a more remote part of the hospital. There are numerous
records of this fly attacking man. It occurs from the Argentine to
Texas.--F. V. T.]
*Chrysomyia viridula*, Rob. Desv.
[This species is somewhat larger than the former; the body is
metallic bluish-green, the dorsum of the thorax with three blackish,
longitudinal stripes, and the face ochraceous; about 10 mm. long.
Austen records this species from man, Dr. Daniels having bred it from
larvæ from a sore on a human being in New Amsterdam, British Guiana.
Dr. Laurence also bred it in Trinidad. In the latter case between 100
and 150 maggots were discharged from the nose of a woman suffering
from facial myiasis (_Brit. Med. Journ._, January 9, 1909, p. 88 +
fig.).--F. V. T.]
Genus. *Lucilia*, Rob. Desv.
*Lucilia nobilis*, Meig.
The larvæ were observed by Meinert in Copenhagen in the auditory
meatus of a person who, after taking a bath, fell asleep in the open
air, and on waking felt singing in the ears, and had a sensation
as if there were water in the auditory canal. During the next days
severe pains set in, and there was a discharge of blood and pus from
both ears, as well as from the nose. On washing out the meatus the
maggots made their appearance.
_Lucilia cæsar_ and _L. sericata_ have also been observed in the
larval state in man (Thompson, Hope, Henneberg and Calendoli, Napoli,
1907).
[This golden-green fly usually lays its eggs on decomposing organic
matter; now and again it lays its eggs in wounds on man.--F. V. T.]
Genus. *Pycnosoma*, Brauer and v. Bergenstamm.
The species of this genus have a general resemblance to the Lucilias
and Chrysomyias, but the body is stouter and the abdomen banded.
The genus can be distinguished from Chrysomyia by the absence of
the three thoracic stripes and by the eyes of the male, in which
the facets forming the upper portion are much enlarged, whereas
in Chrysomyia they are not noticeably larger. Austen also points
out that the sterno-pleural bristles in Pycnosoma are 1 : 1, in
Chrysomyia 2 : 1. The genus is found in tropical Asia and Africa
only. All records of Chrysomyia (Compsomyia) in India must be
referred to this genus. Bezzi and Stein (“Katalog der Palăarktischen
Dipteren,” 1907, iii, p. 543), however, regard the two as synonymous.
The larvæ are frequently found in the nostrils of man and burrow into
the sinus, but normally they live on decaying animal matter.
Pycnosoma forms the so-called Indian screw-worm. Patterson (_Ind.
Med. Gaz._, October, 1909, xliv, No. 10) records the case of a woman
at Tezpin, Assam, from whom as many as 100 larvæ were removed at
one time, and later the left orbital cavity was found packed with
hundreds of maggots; eventually the patient died. It is possible that
this, however, was due to a species of Sarcophaga. Austen undoubtedly
records this genus causing nasal myiasis in India (_Trans. Soc. Trop.
Med. and Hyg._, iii, p. 235). At Dehra Doon, U.P., a woman discharged
100 larvæ from her nose, with great pain in the nasal region and
frontal sinuses.
The so-called “peenash,” a common malady in Rajputana, is a true
nasal myiasis.
Genus. *Sarcophaga*, Mg.
*Sarcophaga carnosa*, L., 1758.
Larvæ of flesh-flies provided with two claws at the anterior end,
which settle on raw or cooked meat, and in the open on carcases
of animals; they are often observed in man, both in the intestine
(introduced with food) and in the nasal cavities, frontal sinus,
conjunctiva, aural meatus, anus, vulva, vagina, prepuce, and open
ulcers, often migrating further from the regions first attacked.
(Gayot in _Compt. rend. Acad. Sci._, Paris, 1838, vii, p. 125. Grube
in _Arch. f. Naturg._, 1853, xix, 1, p. 282. Legrand du Saulle in
_Compt. rend. Acad. Sci._, Paris, 1857, xlv, p. 600, and other
authors.)
[This fly is viviparous. The fly varies from 10 to 30 mm. in length,
and is of a general ash-grey colour; the thorax with three dark
stripes, the abdomen light grey with three black spots on each
segment; legs black; base of wings yellow. It also attacks animals
and birds, especially geese. The genus Sarcophaga is universally
distributed. The maggots are whitish or yellowish footless larvæ of
twelve segments, tapering to a point in front, broadened posteriorly.
There are two mouth hooks, by means of which they rasp their food.
The breathing pores are at the end and consist of two groups of three
slits, each surrounded by a hardened area. They pupate in their old
skin, which turns brown.--F. V. T.]
*Sarcophaga magnifica*, Schiner, 1862.[412]
Syn.: _Sarcophaga wohlfahrti_, Portschinsky, 1875.
[412] [The correct name for this fly is _Wohlfahrtia magnifica_,
Schiner.--F. V. T.]
A species widely distributed over the whole of Europe, occurring
especially in Russia (Mohilew); the presence of the larvæ in man was
first observed by Wohlfahrt (1768). The larvæ settle in the pharynx,
in the nose, the aural meatus, the conjunctiva, and in other regions
of the human body; they also attack domestic animals and birds. As
Portschinsky has shown, they cause severe inflammations, hæmorrhages
and suppurations in the organs in which they occur; children are
especially attacked. A number of cases have been observed also in
Central and Western Europe. [The fly has a light grey abdomen with
shiny black spots which do not change their shape and appearance
according to the angle in which the fly is viewed.--F. V. T.]
(Wohlfahrt: “Observ. de vermibus per nares excretis,” Halæ, 1768;
_Nov. Act. Acad. Caes. Nat. curios._, 1770, iv, p. 277. Gerstäcker
in: _Sitzungsb. Ges. nat. Frde. Berl._, 1875, p. 108. Portschinsky
in: _Horæ soc. entom. ross._, 1875, 1884, p. 123. Laboulbène in:
_Ann. Soc. ent. France_, 1883 (6), iii; _Bull._, p. xcii. Leon in:
_Bull. Soc. des Méd. et Nat. de Jassy_, 1905, xix, p. i. Freund, L.,
in: _Verh. Ges. deutsch. Naturf. u. Ärzte_, Homburg (1902), 1902,
ii, 2, p. 450, and other authors.) [Probably most cases of attack in
Europe are due to this species.--F. V. T.]
The above cited do not exhaust the number of observations of
diptera larvæ parasitic in man; there are yet to be mentioned the
larvæ of _S. hæmorrhoidalis_, _S. hæmatodes_ (of G. Joseph), those
of _S. ruficornis_ (excitants of a cutaneous myiasis in the East
Indies), those of species of Eristalis (of Hanby and others), and
those of _Phora rufipes_ (of Kahl, of Warsaw, and others). In many
cases the determination of the diptera larvæ has been omitted
(or must be omitted); such is the case with diptera larvæ in the
eye (Schultz-Zehden in: _Berl. klin. Wochenschr._, 1906, p. 286.
Ollendorf in: _Med. Korrespondenzbl. d. würt. ärtzl. Landesver._,
1904, p. 1017. Kayser in: _Klin. Monatsbl. f. Augenheilkunde_,
1905, xliii, i, p. 205. Ewetzky and v. Kennel in: _Zeitschr. f.
Augenheilkunde_, 1904, xii, p. 337, and other cases). Austen records
several cases of myiasis due to Sarcophaga (_vide Trans. Soc. Trop.
Med. and Hyg._, 1910, iii, No. 6).
The larvæ of African _Muscidæ_ have now become of greater interest;
like several Oestrid larvæ they live normally in the skin of mammals,
but also attack man. The knowledge of these species is certainly very
insufficient, but this is not likely to be the case much longer, as
medical men practising in the Colonies are giving their attention to
these parasites. At the present time four distinct forms are recognized
according to Gedoelst.[413]
[413] [The following are known to cause myiasis in man in Africa:
_Cordylobia anthropophaga_, Grünb.; _Auchmeromyia luteola_,
Fabr.; _A. rodhani_, Gedoelst; _Oestrus ovis_, Linn.; and
_Anthomyia desjardensii_, Macq. The _anthropophaga_, Blanchard,
and the _depressa_, Walker, referred to here are Grünberg’s
_anthropophaga_.--F. V. T.]
*Sarcophaga chrysotoma*, Wied.
[This species is recorded as attacking human beings at New Amsterdam,
British Guiana. The fly is 15 mm. long, has a golden-coloured
face, three broad black thoracic stripes and ochraceous buff anal
segments. It was bred from larvæ obtained by Dr. Roland from a sore
on a girl’s foot. It is known to occur in the Brazils and the West
Indies. Another species was also bred which Austen was unable to
identify.--F. V. T.]
*Sarcophaga plinthopyga*, Wied.
[This and other species of Sarcophaga are called “yaw flies” in
Dominica, as they are believed to be concerned in the dissemination
of frambœsia or yaws (Nicholls) (_vide_ Austen, _Trans. Soc. Trop.
Med. and Hyg._, 1910, iii, p. 239).--F. V. T.]
*Ochromyia anthropophaga*, E. Blanch.; *Cordylobia arthrophaga*,
Grünberg.
[Illustration: FIG. 409.--Ochromyia larva on the skin of man, South
Africa. 3/1. (After Blanchard.)]
Indigenous to the Senegal and neighbouring districts; in the district
of Cayor (between the mouth of the Senegal and Cape Verde) the larva
is known as the “ver de Cayor.” It lives under the skin, especially
at the lower extremities and the lower region of the trunk, producing
small boils, which cause pain, but after about eight days, when
the larva leaves the body to enter the pupal stage, the pain
discontinues. Besides man the larva occurs in dogs, goats, cats, and
in the jackal. It is still questionable whether the fly deposits its
eggs direct or on the ground, from whence the larvæ as they emerge
gain access to animals and man. Larvæ yellowish-white, 14 mm. long,
4 mm. wide, eleven segments[414]; head with two globular antennæ-like
appendages, two black curved mouth hooks, and two wart-shaped, finely
spinous structures at their base. Body evenly covered to the seventh
segment with small black prickles, which are stronger at the sides
and the anterior borders of the segments; from the seventh they
increase in size, on the two hindermost they are wanting; on the last
segment two deep yellow spiracles, each with three markedly curved
fissures; in addition two stigmata on the posterior border of the
first segment. Duration of the larval stage about eight days. Upon
the construction of roads in Guinea the larva is spread by dogs far
into the interior.
[414] [Austen gives the length as 12 to 12·5 mm. and the breadth as
5 mm.; he describes the larva as follows: Bluntly pointed at the
anterior extremity, and truncate behind; from third to eleventh
segments thickly covered with minute recurved spines of brownish
chitin, usually arranged in transverse series of groups of two or
more, which can be seen to form more or less distinct undulating
and irregular transverse rows. In each of the two posterior
stigmatic plates, the respiratory slit on either side of the median
one is characteristically curved, resembling an inverted note of
interrogation. The barrel-shaped puparium is on an average 10·3 by
4·6 mm.; its colour varies from ferruginous to nearly black.--F. V. T.]
*Auchmeromyia* (*Bengalia*) *depressa* (Walker).[415]
[415] [According to Austen this is _Cordylobia anthropophaga_, Grünb.
_Bengalia depressa_, Walker, is a very different insect, whose
life-history is unknown.--F. V. T.]
[Illustration: FIG. 410.--Head end of “larva of Natal.” Magnified.
(After Gedoelst.)]
Distributed in the region of Natal and apparently over the whole of
South Africa. The “larva of Natal,” as one may still term the species
provisionally, as its identity is not certain, possesses on its head
(besides the mouth hooks) lateral protuberances beset with a row of
chitinous spines. The cuticle of the body is spinose. The spines are
difficult to recognize on account of their transparency and want of
colour; they are longest over the anterior segments, from the fifth
they become smaller, and over the hindermost they are very small.
Apart from the foremost segment, the position they take is that of
rows running transversely or obliquely, two to four generally in
juxtaposition; the number of spines in the groups gradually increases
posteriorly, attaining the number of eight to twelve on the sixth
segment, and this number is maintained to the end of the body.
Isolated spines are found over the head; over the second, third and
fourth segments single ones are still found adjoining the groups
of spines, from the fifth onward they are wanting. From here the
spines cover the whole free surface of the segments; over the fourth
the anterior three-quarters, over the third two-thirds and over the
first and second only the anterior half. The stigmata found at the
anterior end also serve as distinguishing characters. The parasitic
stage appears to last about fourteen days. [Fuller (_Agric. Journ._,
Dept. Agric. and Mines, Natal, 1901, iv, p. 606) refers to this as
_Bengalia depressa_ also.--F. V. T.]
Genus. *Cordylobia*, Grünberg, 1903.
*Cordylobia grünbergi*, Dönitz.
Syn.: _Ochromyia anthropophaga_, Grünberg, _nec_ Blanch.; _Cordylobia
anthropophaga_, Grünberg.
Endemic in German East Africa and neighbouring regions. Larva up
to 14 mm. long, 4 to 5·5 mm. wide, of cylindrical shape, slightly
narrowed behind, truncated, gradually tapering in front; antennæ-like
processes, cone-shaped, blunt. Smaller cylindrical formations at the
base of the mouth hooks surrounded by a circle of chitinous hooks.
Body from the first segment covered with small brown squamous spines
which are disposed in numerous irregular transverse rows. The spines
are small over the two first segments, the two posterior thirds of
all the segments, as well as from the eighth; over the third to the
seventh they are larger, but between these there are very small
spines. The breathing pores of the stigmata at the anterior end are
kidney-shaped; the orifices are elongated and very tortuous, each
divided into three. The larval period appears to last several weeks.
*Cordylobia anthropophaga*, Grünberg.
This well-known cutaneous African parasite seems to have been the
cause of much confusion in regard to names. It belongs to the genus
Cordylobia of Grünberg, and is one of the family _Muscidæ_, and
differs from Auchmeromyia in that the second abdominal segment of
the female is of normal size, whilst in Auchmeromyia it is more than
half the length of the whole abdomen, and in the male the eyes are
holoptic or close together, whilst in Auchmeromyia they are wide
apart. The flies of this genus (three so far described) attack man in
their larval stage (anyway two of the three), and also dogs and other
animals, by burrowing into the skin and producing painful boils.
[_C. anthropophaga_, Grünberg, is widely distributed in Africa,
extending from Senegal, where its maggot is known as the “ver de
Cayor,” and is referred to on p. 590 as _Ochromyia anthropophaga_,
E. Blanchard, to Natal, where it is known as the “Natal worm,” and
referred to erroneously on p. 591 as _Bengalia depressa_, Walker.
[It is a thick-set Muscid of a general straw-yellow colour, with
blackish markings on the dorsum of both thorax and abdomen, about
9·5 mm. long. The larva is fat and when mature about 12 mm. long,
bluntly pointed in front, truncate behind; from the third to eleventh
segments it is thickly covered with minute recurved spines of a
brownish colour, arranged in transverse series of groups of two or
more, which form more or less distinct irregular transverse rows.
On each of the two posterior stigmatic plates, the respiratory slit
on either side of the median one is characteristically curved,
resembling an inverted note of interrogation. The puparium is brown
to ferruginous or black and about 10 mm. long. The maggots are
found in both natives and white men, and occur as a severe pest in
dogs, also in monkeys, rats, and other mammals. In Sierra Leone it
is called the “tumba fly.” The larvæ have been frequently found as
true subcutaneous parasites, each larva living singly and forming a
boil or warble in the skin, with an opening just as in an ox-warble,
through which the maggot breathes and eventually escapes. Although
they more usually occur as isolated specimens, Marshall found in
Salisbury, South Rhodesia, that sixty were extracted from one lady,
and Bérenger-Féraud, in Senegal, that more than 300 occurred in a
single spaniel puppy.
[Neave (_Bull. Ent. Res._, 1912, iii, p. 217) records it from ulcers
in a native at Lourenço Marques in 1908, and at the same time from
ulcers in a dog, and that it is a severe pest to man in Mozambique
and parts of the Transvaal. It seems to be more abundant in North
Rhodesia and Nyasaland than to the north (Neave, _Bull. Ent. Res._,
1912, iii, p. 310). It is also recorded in Zanzibar, German East
Africa, Uganda, East Tropical Africa (Neave).
[Simpson (_Bull. Ent. Res._, iii, p. 170) records a Muscid larva
taken from the breast of a European in South Nigeria that was
probably Cordylobia.
[It is not known how infection takes place. Neave (_Bull. Ent. Res._,
iii, p. 310) says: “Many instances in human beings would preclude
the possibility of eggs having been laid direct on the skin: in these
cases they have probably been laid on the clothing put out to dry.”
[Gedoelst has described another species, _C. rodhani_, and Austen
a third species, _C. prægrandis_, from Nyasaland, Cape Colony,
Transvaal, Natal, North-west Rhodesia, and German East Africa.
[The following are some papers dealing with this subject: _Proc. Ent.
Soc._, London, for year 1907, p. xlvii; _Journ. R.A.M.C._, 1908,
pp. 5–11, figs. 1 and 2, by Austen; _Journ. R.A.M.C._, 1908, pp. 1
and 2, by Major F. Smith; _Trans. Soc. Trop. Med. and Hyg._, 1910,
iii, pp. 223–225, by Austen.--F. V. T.]
*Lund’s Larva.*
[Illustration: FIG. 411.--Lund’s larva: on the left, the whole larva,
magnified six times. On the right, the head end, much enlarged. (After
Gedoelst.)]
Endemic in the region of the Congo State; called after Commander
Lund, from the skin of whose arm it was extracted; 12·5 mm. long,
4·5 mm. broad; colour yellowish, with brown rings, on account
of the division of the brown spines; head cone-shaped, with
two hemispherical smooth antennæ, two thick black mouth hooks
and wart-shaped bodies, between which are situate two to three
longitudinal rows of dark brown chitinous laminæ. The body segments
are covered over their whole surface with irregularly distributed
triangular yellow spines, the points of which are coloured dark
brown. Its size increases from the second to the sixth segment,
diminishes from the seventh to the ninth, at the tenth it is
reduced, and at the eleventh quite small. The posterior stigmata are
bean-shaped, each with three markedly tortuous openings. Duration of
the larval stage unknown; the same applies to the pupal and imago
stages.
*Auchmeromyia luteola*, Fabricius.
[This fly, the parent of the so-called Congo floor maggot,[416]
belongs to a nearly allied Muscid genus to Cordylobia, but which
can at once be told by the great length of the second abdominal
segment. The maggot occurs in numbers in the native huts in the
Congo region and is fairly common in central and northern parts
of Mozambique; it is also recorded from the Zambesi River and the
vicinity of Barberton in the Eastern Transvaal (_Bull. Ent. Res._,
1912, iii, p. 216), in German East Africa, in Nyasaland, and British
East Africa. It is also recorded from Bara, Kordofan,[417] where they
occurred on the floor of the men’s prison and bit the prisoners.
They were destroyed by sprinkling Jeyes’ fluid on the floor. Neave
states (_ibid._, p. 310) that it occurs in the more neglected huts
in native villages throughout tropical Africa, and frequently enters
a tent when pitched near a village. It is also found in West Africa.
The fly is thick-set and about the size and build of a bluebottle
fly; length 10 to 12 mm.; tawny in colour to dirty yellowish-brown,
with dusky hairs, giving it a smoky appearance; the flattened thorax
has long dark stripes and the abdomen a dusky line in the centre of
the second segment, which meets a dark line on its posterior border;
the dusky third segment has a narrow yellowish anterior line; the
fourth segment is also dusky; legs buff with black hairs; the fifth
tarsal segment black. The larvæ are whitish, becoming reddish after
a feast of blood, with much wrinkled skin and rather flat and broad.
They live in crevices of the mud floor, under sleeping mats during
the daytime, and come out at night and suck the blood of sleepers
and then retire to shelter again. Dutton, Todd, and Christy noticed
that where people slept on beds or platforms raised above the floor
the maggots were not so numerous as under the sleeping mats laid on
the ground. They turned up many of the maggots from a depth of three
inches or more.[418]--F. V. T.]
[416] Dutton, Todd and Christy, “The Congo Floor Maggot,” _Mem. xiii
Liv. Sch. Trop. Med._, p. 40.
[417] Balfour, _Journ. Trop. Med_., 1909, xii, No. 4, p. 47.
[418] _Journ. Trop. Med._, 1905, viii, No. 6, p. 90.
Family. *Oestridæ.*
[The family of _Oestridæ_ or warble flies are all parasitic in their
larval stage, usually termed the “bot” stage. They are found as
parasites in warm-blooded animals, and man is frequently attacked
by them. The members of this family have the mouth rudimentary,
many of them are hairy and bee-like, with large eyes and the head
large, the lower part more or less swollen. The thorax is large with
a distinct transverse suture, and the abdomen short and stumpy or
very slightly elongated. The male genitalia are hidden, whilst the
female ovipositor is often elongated. The wings may be transparent
(Hypoderma) or mottled (Gastrophilus), and have muscid-like venation;
the tegulæ usually large, the legs moderately long.
[As a rule each species is confined to a particular host, but as we
see recorded here those that attack animals may also attack man.
The flies occur in warm weather and usually during the warmest
part of the day, and have a strong dislike to shade and water. The
genus Hypoderma attack oxen, sheep, goats, antelope and musk deer;
Oestrus, sheep, antelope and horses; Gastrophilus, the horse and
ass; Cephenomyia, the deer; Cepholomyia, the camel and buffalo;
Dermatobia, dogs, cats, oxen, deer, apes and man; Cuterebra and
Rogenhofera, rodents and opossums.
[Some live as parasites in the stomach and intestines (Gastrophilus);
others infest the skin (Hypoderma, Dermatobia and Oestromyia, the
latter on _Lagomys_ and _Hypodæus_); _Œdemagena tarandi_ also infests
the skin of the reindeer in Siberia and boreal America. Oestrus lives
in the nasal sinus, and Cephalomyia in the throat as well, Cuterebra
and Rogenhofera, the skin or scrotum, so that we have really three
groups of parasitic oestride larvæ: (i) cutaneous, (ii) intestinal,
and (iii) facial.
[No species seems confined to man, but the so-called “creeping
disease,” caused by Hypodermæ, and the attack of sheep nasal fly are
comparatively common, as also is the Dermatobia attack.--F. V. T.].
CUTANEOUS OESTRIDÆ.
The eggs are deposited on the surface of the body; the larvæ burrow
in the skin, which they reach after somewhat long peregrination.
Genus. *Hypoderma*, Latreille.
*Hypoderma bovis*, de Geer.
The cattle fly or warble fly, which swarms during the hot season,
settles on the head or on the hair of grazing cattle: through
the young being licked off they gain access to the mouth and are
swallowed.[419] The larvæ appear first in the commencing portion of
the stomach, to escape, as some state, into the preceding sections of
the alimentary canal; at any rate, they are found from July onward
regularly in the submucous tissue of the pharynx, in which they
travel about for several months (up to November, and in isolated
cases up to February); they then penetrate the muscularis and migrate
by way of the subserosa along the mediastinum, the crura of the
diaphragm, the renal capsules, and the intermuscular connective
tissue of the psoas muscle in the direction of the spinal canal,
into which they penetrate by way of the muscles and nerves, through
the intervertebral foramina. Here they stay for about two to three
months, then they leave the spinal canal again through the vertebral
foramina and make their way (from January to March) through the
intermuscular connective tissue of the muscles of the back to the
skin of the back, where sooner or later (from January to June) they
arrive and enter a resting stage, which commences with penetration of
the skin and terminates with outward migration from the boils due to
the wound set up by the maggot. At the commencement of this period
the larvæ cast their skin, and their form, hitherto cylindrical,
becomes oval. After about a month, a second moulting of the skin
takes place--the third larval stage, which lasts about two and a half
months (up to June). The approaching end of the same is indicated
by a change of colour on the part of the larva from the hitherto
yellowish-white to brown and finally to blackish-brown. When they
have become mature the larvæ leave the warbles, drop on to the ground
and pass into the pupal stage in the superficial layers of the soil
within twelve to thirty-six hours. After about a month the flies
emerge. Irregularities with regard to the time and direction of the
migrations of the larvæ take place (Jost, H., in _Zeitschr. f. wiss.
Zool._, 1907, xxxvi, p. 644).
[419] [This is not the case, for Carpenter has shown that muzzled
calves become infected (“Mém. First Int. Cong. Ent.,” pp. 289–293).
Jost (_Zeitschr. f. wiss. Zool._, 1907, xxxvi, pp. 644–715)
thinks that the ova, not young larvæ, are ingested (vide note in
Supplement).--F. V. T.]
In a number of cases the larva of the cattle fly has been observed in
the human integument, usually in the winter months, that is, during the
migration period; consequently, it is not surprising that the larvæ
before they enter on the resting stage and produce a warble undergo
migrations. But that this takes place subcutaneously--which does not
appear to be so in the case of cattle--is perhaps explained by the fact
that in man, on account of the short space that has to be traversed,
the larvæ are not sufficiently developed to enter on the resting stage
simultaneously upon having obtained access to the integument. Whether
the Oestrid larvæ in Bulgaria that similarly migrate beneath the skin
in man belong to the cattle fly or to another species, or even another
genus, has not yet been ascertained. (Doctorow, in _Arch. de Par._,
1906, x, p. 309; Spring, A., in _Bull. Acad. sci. Belg._, 1861 (2), iv,
p. 172; Walker, R., in _Brit. Med. Journ._, 1870, i, p. 151; Kjelgaard,
in _Ugeskr. f. Laeger_, 1904, p. 535; Condorelli, M., in _Bull. Soc.
Zool. Ital._, 1904, xiii, p. 171.)
*Hypoderma lineata*, de Villers.
The larvæ of this species, that occurs not only in Europe but in
North America, live under similar conditions in the skin, very rarely
in man; also migrating subcutaneously (Topsent in _Arch. de Par._,
1901, iv, p. 609).
[In Sweden, the ox warble fly (_H. bovis_) is well known to attack
man. Schoyen states “that over 100 years ago up to the present time
cases of travelling grubs under the human skin in some districts of
Sweden were well known.” The species appeared to be _H. bovis_, many
of which he had examined. They accomplished long ramblings under the
skin, always in an upward direction, previous to their appearance
through an opening in a tumour on the upper part of the body, on the
head, neck, or shoulders. An interesting case is recorded in _Insect
Life_, ii, pp. 238–239. A bot similar to _H. diana_ was taken from
the eye and cheek of a child at Kane, McKean County, Pa., U.S.A. It
was said to have travelled in five months from the elbow to the eye.
Riley later (_Insect Life_, iv, p. 310) was inclined to think the
maggot was that of _H. lineata_, the common American ox warble, which
is also found in Europe in great numbers. I have recorded another
case in England (_Rept. Econ. Zool._ for year ending September 30,
1910, p. 128), where Dr. Menzies removed the larva of _H. bovis_
from the upper eyelid of a patient. It caused considerable swelling
of the face, much pain and distress; but the case did well, and the
wound healed at once. The larva was nearly mature. Numerous other
references to this so-called creeping disease will be found in the
Supplement.
[It is quite probable that _bovis_ and _lineata_ are confused in the
latter accounts. The larvæ are, however, easily distinguished if
carefully examined.--F. V. T.]
*Hypoderma diana*, Brauer.
In its larval stage it lives like other species of Hypoderma,
attacking the red deer (_Cervas elaphas_) and roe deer (_Cervas
capreolus_); it is occasionally also found in man (Joseph, in
“Myiasis externa dermatosa,” Hamburg, 1800; Völkel, in _Berl. klin.
Wochenschr._, 1883, xx, p. 209).
Genus. *Dermatobia*, Brauer.
*Dermatobia cyaniventris*, Macq.
Syn.: _Dermatobia noxialis_, J. Goudot.
The genus Dermatobia represents the subcutaneous _Oestridæ_ of Europe
in warmer parts of America. Both domesticated and wild mammals are
attacked, according to one statement birds also (_Ramphastus_), and
man with fair frequency.[420] It is assumed that in all cases one and
the same species is concerned, for which recently a name originating
from C. Linné, jun. (_Oestrus hominis_), has been employed. Three
larval stages are recognized in the skin; the two first appear to
resemble one another in the club-shaped or tadpole-like appearance
(called macaque in Cayenne, mayacuil [mayoquil] in Mexico), the third
is swollen spindle-shaped (Berne, called torcel). Segments 2 to 4
in the club-shaped larvæ are closely beset with small black spines,
segments 5 to 7 bear at the anterior border a complete ring of strong
black hooks, segments 4 to 6 a similar ring, which, however, is
interrupted at the ventral surface. The four last segments forming
the tail are smooth, only at the posterior end are there small
spines. The arrangement of spines of the third stage differs from
this. Italian workmen that have been employed in Brazil show the
presence of Dermatobia larvæ on their return (Blanchard, in _Bull.
Soc. Ent. France_, 1893, p. 24; _Bull. Soc. centr. de Méd. vet._,
1896; _Ann. Soc. Ent. France_, 1894, lxiii, p. 142; Ward, H. B., in
Mark Annivers. Vol., Article 25, p. 483, New York, 1903).
[420] Duprey advances the opinion that Dermatobia deposits its eggs not
only on the skin of man and animals, but also on the leaves and twigs
in the bush, where, too, young larvæ have been met with which gain
access from hence to men and animals (_Journ. Trop. Med. and Hyg._,
1906).
[Illustration: FIG. 412.--_Dermatobia noxialis_, Goudot.]
[Illustration: FIG. 413.--Larva of _Dermatobia cyaniventris_ in its
natural size and magnified. (After Blanchard.)]
[Illustration: FIG. 414.--Larva of _Dermatobia cyaniventris_. Enlarged.
(After Blanchard.)]
[_Dermatobia cyaniventris_, Macquart, 1843, is said not to be the
same as _noxialis_ (_vide_ Brauer, “Mono. Oestriden,” 1863, p. 266).
It is known by various other names, as nuche or gusano in New
Granada, the ura in Brazil, and the macaw fly in Cayenne. It occurs
in Central and South America and the West Indies. According to Goudot
the fly is found in great numbers on the borders of large woods and
lands covered with underwood.
[It is seldom that more than one larva is found in each individual.
It is generally found in the arm and leg, but now and then the face.
The perfect insect has never been bred from a larva removed from a
human being, so that there is still uncertainty as to the actual
species. _D. cyaniventris_ is 11 to 12 mm. long, has an ochraceous
buff-coloured face, dark grey thorax, metallic dark blue to purple
abdomen, and brownish wings. _D. noxialis_ is somewhat larger.
[In the _Journal of Tropical Medicine and Hygiene_, January 15, 1905,
viii, p. 23, reference is made to this Oestrid in Trinidad, where
it is called the “mosquito worm.” One case here recorded showed no
fewer than four worms on the chin and one on the hand. It is here
stated that the fly never attacks man or animals directly, as it is
said to do by Scheube, but that the eggs are deposited on leaves and
branches in wooded lands and forests, and thus man, hunting dogs
and wild animals in passing through get the larvæ deposited on them
accidentally. The affection is common in Trinidad. Mention is made
that a little 1 in 40 carbolic lotion syringed into the aperture in
the skin over the worm quickly killed it.
[The cattle worm, or founzaia ngómbe, is the name given to a larva
which develops beneath the skin of oxen and men in Central Africa,
especially amongst the natives and stock of Unyamonezi. According to
P. Dutrieux, the egg is laid by a large fly that accompanies cattle.
It is unknown between the central plateau or the Ugogo and the East
Coast.--F. V. T.]
CAVICOLOUS OESTRIDÆ.
The forms belonging to this group inhabit as larvæ the nasal and
frontal sinuses of ruminants, _Equidæ_ and _Proboscidæ_, which they
leave for the pupal stage. The larva of--
Genus. *Oestrus*, Linnæus,
*Oestrus* (*Cephalomyia*) *ovis*, L.,
occurring in sheep, has also been observed in man in six cases in the
nose and larynx (Saitta in _Gaz. d. Osp. d. Clinic_, 1903, No. 128). So
far as is known, the eggs are deposited in the nasal cavity.
[_Oestrus ovis_ frequently occurs in man. MM. Sergent (_Ann. de
l’Inst. Pasteur_, 1907, pp. 392–399) mention that they lay their ova
on the noses, eyes and mouth of humans in Algeria whilst flying,
but that they disappear after three to ten days or the inflammation
produced by them. Portschinsky (_Mem. Bur. Ent. Sci. Com. Cent. Bd.
Land Adm. and Agric._, 1913, x, No. 3, p. 63) also gives cases. He
doubts that ova are laid on the nose; evidently the Russian habit is
anomalous, for the Sergents, Collings and myself find ova laid as a
common occurrence. I have often seen them on the nose of sheep. This
fly also occurs in the Argentine (Serres, in _Gaceta Rural_, April,
1913, vi, pp. 759–761).
[The tamné or thimni of the Kabyles, a human myiasis of the Tuareg
mountains in the Sahara, is caused by _Oestrus ovis_. Here the larvæ
are said to be ejected on to the conjunctival and nasal mucous
membrane of humans.
[Ed. and Lt. Sergent (_Bull. Soc. Path. exot._, 1913, vi, No. 7,
pp. 487–488) report their attack from the Ahaggar mountains, in
Central Sahara. The Tuareg name for the fly, tamné, is the Targui
form of the word thimni used by the Kabyles.--F. V. T.]
GASTRICOLOUS OESTRIDÆ.
The eggs are deposited on the hairs of _Equidæ_, and the larvæ escaping
from them are licked up and swallowed. They pass their larval stage,
according to the species, in various parts of the intestine and
stomach, and when mature, pass out _per anum_ in order to undergo the
pupal stage.
Genus. *Gastrophilus*, Leach.
One of the most frequent species is _Gastrophilus equi_, Fabr.;
the eggs are laid on the hairs; the larvæ live some ten months in
the stomach, living attached to the inner surface. The eggs of _G.
hæmorrhoidalis_, L., are deposited on the lips or the long hairs on
them. The larvæ adhere to the cardiac end of the stomach, to the
stomach itself, and finally to the terminal portion of the intestine.
Here, however, and elsewhere in the intestine, the larvæ of _G.
pecorum_, Fabr., are also met with, whilst the larvæ of _G. nasalis_
(so called because the eggs are deposited in the nasal orifices)
almost exclusively inhabit the anterior section of the duodenum.
Cholodkowsky attributes the “wormlet” observed by Samson and Sokolew
(_Wratsch_, 1895, Nos. 48 and 57) and others (_ibid._, 1896–98)
to _Gastrophilus_ larvæ. It burrows into the epidermis of man by
minute passages. This observation should, however, be verified. The
phenomenon is designated as skin-mole, larva migrans, and creeping
eruption.
OTHER PAPERS ON DIPTEROUS LARVÆ, ETC., IN MAN.
(1) “Ein Fall von lebenden Fliegenlarven im menschlichen Magen,”
_Deutsch med. Wochenschr._, Leipz. and Berl., xxiv (12), pp. 193–194.
Bachmann, and review of same, “Living Fly Larvæ in the Human
Stomach,” _Philadelphia Med. Journ._, 1898, i, 18, p. 773.
(2) “Sudi una larva di dittero parassita della congiuntiva umana,”
_Ann. di ottal._, Paira, 1895, xxiv (4), pp. 329–336, 1 fig., E.
Baquis.
(3) “Sur quelques diptères suceurs de sang, observé à Terre-Neuve,”
_Arch. de Par._, Paris, 1900, iii (1), pp. 202–204, E. Barret.
(4) “An Account of the Larvæ of two Species of Insects discharged
from the Human Body,” _Edin. Med. and Surg. Journ._, January 1, 1811,
vii (25), pp. 41–48, 1 pl., figs. 1 to 8, T. Bateman.
(5) “Un cas de myiase par la _Sarcophaga magnifica_ en Roumanie,”
_Bull. Soc. Zool. de France_, Par., 1891, xvi (2), pp. 25–26, R.
Blanchard.
(6) “Sur les oestrides américains dont la larve vit dans la peau
de l’homme,” _Ann. Soc. ent. de France_, 1892, v, pp. 109–154,
figs. 1–12, R. Blanchard.
(7) “Note additionnelle sur les oestrides américans dont la larve vit
dans la peau de l’homme,” _Bull. Soc. ent. de France_, Paris, 1894,
xiv, pp. 209–211, R. Blanchard.
(8) “Note sur des larves de Dermatobia provenant de Brésil,” _Bull.
Soc. ent. de France_, Paris, 1893 (2), pp. 24–27, R. Blanchard.
(9) “Larven der Wohlfahrtfliege (_Sarcophila wolfahrtii_) im
Zahnfleische eines Menchen,” _Wratsch._, St. Petersburg, 1888, 5–6,
E. K. Brandt.
(10) “Ueber den sogenannten _Oestrus hominis_ und die oftmals
besichteten Verirrungen von Oestriden der Säugetheiere zum Menchen,”
_Verhandl. d. k. zool.-bot. Gesellsch._, 1860, x Abhandl., pp. 57–72,
Brauer.
(11) “Ueber die Larven der Gattung Cuterebra, Clk.,” _Verhandl. d. k.
zool.-bot. Gesellsch._, 1860, x Abhand., pp. 777–786, Brauer.
(12) “Des désordres produits chez l’homme par les larves de la
_Lucilia hominivorax_,” _Thèse_, Paris, 1864, 43 pp., V. Audouit.
(13) “Note on the ‘Flesh Worm,’” _Med. Press and Circ._, London,
April 12, 1882, lxxxii (N.S. xxxiii), p. 314, P. S. Abraham.
(14) “Larvas de la _Calliphora limensis_ en fosas nasalis,” 1855, 18
pp., F. Aguirre.
(15) “Raro caso di parasitismo nell ’uomo dovuto alla larva di una
mosca (_Sarcophaga affinis_, Meigen),” _Boll. d. Soc. Rom. per gli
Stud. Zool._, Roma, 1893, iv (5–6), pp. 278–289, 1 pl., 3 figs.,
Giulo Alessandrini.
(16) “Observations sur l’espèce de ver nommé Macaque (Oestrus),”
_Mém. Acad. Sci. par Hist._, 1753, p. 72, F. Artur.
(17) “Contribuição ao estudo da biologia da _Dermatobia
cyaniventris_,” _Trav. do Inst. de Manguinhos_, 1908.
BITING-MOUTHED AND OTHER NOXIOUS DIPTERA WHICH MAY BE DISEASE CARRIERS.
[Amongst the division _Brachycera_ (as meant in this work) we get
several groups of flies which, like the fleas and mosquitoes, are
partially parasitic on man, the adults, mainly in the female sex,
being provided with a piercing mouth with which they extract the
blood of man and animals. The importance of these parasites is not
the mere fact that they feed upon our blood, but that they often
carry germs from man to man (tsetse-flies and trypanosomiasis,
_Tabanidæ_ and anthrax). Amongst the most important biting-mouthed
_Diptera_ in this section are the following: _Tabanidæ_, or
gad-flies; _Glossinæ_, or tsetse-flies; and certain other _Muscidæ_.
Some of the exotic _Asilidæ_ and a few _Leptidæ_ also bite man.
Family. *Tabanidæ* (Gad-flies).
[The _Tabanidæ_ have a broad, rather flattened body and a large head;
eyes united in the male (except in some Chrysops). The antennæ are
composed of three segments, have the third joint composed of five
to eight annuli--in Chrysops they are fairly long. The proboscis is
projecting, and sometimes much elongated. The legs are moderately
stout. The venation of the wings is shown in fig. 415.
[This family of gad or horse flies contains a great number of genera,
all of which may bite animals and man more or less severely. The
female alone is blood-sucking, the males feed upon the juices of
flowers. The females deposit their spindle-shaped white, black,
or brown eggs on leaves, stems of plants that either overhang or
stand in water, and amongst rushes; they are at first white, but
become brown or black. The eggs are laid in rounded, flattened or
conical masses composed of layers one upon the other. The larvæ are
carnivorous, feeding upon snails, worms, other larvæ, etc., and have
a distinct head; they are cylindrical, composed of eleven segments,
the last with a vertical breathing pore, or the last two segments may
form a breathing tube. The majority taper to a point at each end, in
colour shining white or dull grey to yellowish, many of the larger
specimens mottled or banded with dark brown or black. The first seven
abdominal segments are encircled near the anterior margin with a
ring of fleshy protuberances consisting of a transverse dorsal ridge
which may be divided by a depression into two. The young larvæ burrow
into any soft vegetable substance; they live both in the water and
under damp soil surrounding water, also in damp earth generally. The
larvæ are not only carnivorous, but they are cannibals, frequently
devouring their own species. They may take more than a year to mature.
[The pupæ are found close to the surface of mud and earth, and are
mostly dull yellowish to brown in colour, with rows of spines on the
distal third of each abdominal segment; the thorax bears a pair of
ear-shaped spiracular structures, and there are also six denticles at
the apex of the abdomen.
[A habit common to the adults of most of the _Tabanidæ_ of
considerable economic importance is that of the adults coming to
water to drink. Portschinsky[421] has found that by applying kerosene
to the pool they frequent the adults are killed, and Hine[422] that
the same oil kills the larvæ that fall into the water from eggs laid
on plants above.
[421] _Vide Bull._ 20, _N. Sc., U.S. Div. Ent._
[422] “_Tabanidæ_ of Ohio,” _Ohio State University Bull._ 19, 1903,
sec. 7, p. 14.
[_Tabanidæ_ are not only of importance as purely biting insects,
for they may often convey pathogenic organisms from one animal to
another, such as the bacillus of anthrax, which they are known to
carry, and possibly also trypanosomes in regard to man. Chrysops also
acts as a host of _Filaria loa_ in South Nigeria (Leiper, _Brit. Med.
Journ._, January, 1912, pp. 39–40). Two species are incriminated,
_viz._, _C. silacea_ and _C. dimidiata_. With animals these flies
play a more important part, for MM. Sergent, in Algeria, have proved
that species of Tabanus are able to transmit three forms of animal
trypanosomes by biting a healthy animal as long as twenty-two hours
after having bitten an unhealthy one. In India they have also been
shown to transmit the parasite of “surra” in dogs and rabbits by
Rogers. Other observers have since corroborated these results,
and Mitzmain, who has recently performed valuable work in this
connection, states that _T. striatus_ is undoubtedly the carrier
of this disease in the Philippine Islands. Certain members of the
genus Hæmatopota have also been shown to be capable of the direct
transmission of _Trypanosoma evansi._ Martoglio (_Ann. d’Ig. sper._,
1913, xxiii, N.S., No. 3, pp. 363–366) states that the trypanosome
disease of dromedaries known as salaf is transmitted by _Tabanidæ_,
especially Pangonia (_P. magretti_ and _P. beckeri_) in Italian
Somaliland. It is quite likely that these flies play a much greater
part in the spread of such diseases than is imagined at the present
time.
[Illustration: FIG. 415.--The ox gad fly (_Tabanus bovinus_, Linn.).]
[The _Tabanidæ_ are divided into two groups or subfamilies: (1) The
_Pangoninæ_, and (2) the _Tabaninæ_; the former have spurs on the
hind tibiæ and usually ocelli; the latter have neither tibial spurs
nor ocelli.
[The _Pangoninæ_ contain two main genera, Pangonia and Chrysops. In
the former the proboscis is much elongated, and the third antennal
segment is composed of eight rings, and is never angulated or
ungulated at the base. The proboscis is often very long.
[In Chrysops, the so-called blinding storm flies, all the three
segments of the antennæ are long, the third having only five
annulations, and the proboscis short but very strong.
[There are many genera in the _Tabaninæ_, which are found in all
parts of the world, of which two only are shown here--_viz._,
Tabanus and Hæmatopota. The former has the first two segments of the
antennæ short, the third angulated at the base, sometimes spurred
and composed of five annulations; the second has the second segment
short, and the third composed of four annulations--never angulated
nor spurred at the base--and the wings are adorned with grey or brown
markings. These latter are usually called “brimps” and “clegs” in
Britain, the former gad or horse flies, the seruts and mangrove flies
of tropical countries.
[Illustration: FIG. 416.--The brimp (_Hæmatopota pluvialis_, Linn.).]
Family. *Asilidæ* (Wolf Flies).
[These flies are of little importance in regard to the subject dealt
with in this book; but I have notes sent concerning the biting habits
of one or more species belonging to this family from the Malay States
and Africa.
[_Asilidæ_, or wolf flies, are easily told by the following
characters: Large or moderate-sized flies, thickly hairy; head
separated from thorax by a narrow neck; eyes separated in both
sexes; proboscis firm and horny, adapted for piercing; abdomen long,
pointed, and composed of eight segments. Legs strong and bristly,
of moderate length. Wings sometimes mottled, lying parallel over
the abdomen when at rest. There are nearly 3,000 species. They live
mostly upon insects, but some are said to bite animals and man. They
are, however, of little importance in this respect.
Family. *Leptidæ.*
[This widely distributed family of flies has a few species which suck
the blood of man, and the writer has been personally badly bitten in
Norway by a Leptis which was apparently _Leptis scolopacea_.
[The _Leptidæ_ have usually blotched wings and similar venation to
Tabanus; they are elongated flies of moderate or large size, and of
dull colours. The antennæ are varied and consist of three segments,
either with or without a terminal bristle or with the third segment
compound, and in a few they may be almost nematocerous. The wing
veins are distinct, very crowded anteriorly, the third long vein is
furcate, basal cells large, and there are usually five posterior
cells, the anal cell being open in some; the squamæ are always small,
sometimes only rudimentary.
[Four are known to be blood-suckers, namely the American
Symphoromyia, _Trichopalpus obscurus_ in Chili, and _Leptis strigosa_
and _L. scolopacea_ in Europe. The genus Symphoromyia has a single
spur on the hind tibiæ, none on the fore or mid tibiæ, the third
segment of the three-ringed antennæ kidney-shaped, and a short
proboscis. In the genus Leptis the hind tibiæ have two spurs, and the
third antennal segment is not reniform.
[The other biting genus Trichopalpus can be told at once by the
elongated proboscis. Most of this family live upon other insects. The
larvæ live in earth, decaying wood, sand, stagnant waters, and the
nests of wood-boring beetles; they are usually cylindrical and may
have fleshy abdominal legs; the anal segment has a transverse cleft,
and often two posteriorly directed processes and two stigmata between
them. They are all predaceous, and in one genus (Vermileo) make
pitfalls in sand like the ant lions (_Myrmeleon_).
Blood-sucking Muscidæ.
[The blood-sucking _Muscidæ_ are mainly contained in the following
genera: Glossina, Stomoxys, Hæmatobia, Lyperosia, Stygeromyia,
Philæmatomyia and Bdellolarynx.
[The first is the most important genus on account of the part it
plays in the spread of trypanosome diseases. Stomoxys may also serve
as a disease carrier. The remainder and a few more genera cause
considerable annoyance by their bites, and may also act as occasional
carriers of pathogenic organisms. All these flies have their mouth
parts elongated to some extent, forming a distinct proboscis, which
becomes more or less strongly chitinized; the labella are usually
serrated or spiny, and thus form a structure easily capable of
piercing the skin. Unlike the _Culicidæ_, the blood-sucking _Muscidæ_
have the sanguinary habit common to both sexes.
Genus. *Glossina*, Westwood.
[This genus contains sixteen species,[423] all of which are
confined to the Ethiopian region. Glossina may be distinguished
from other allied genera by the proboscis, the antennæ, wings, and
male genitalia. The proboscis projects forwards and has a swollen
bulb-like base to the slender labium which holds the two structures,
the needle-like epipharynx and the thread-like hypopharynx; the whole
proboscis is ensheathed in the maxillary palpi. The antennæ have the
first two segments small, the third large with a marked pore, the
orifice of the sense organ near the base; from the base of the third
segment also arises the three-jointed arista, the first two segments
being, however, minute; the third bears a series of from seventeen
to twenty-one fine branched hairs on one side. The male genitalia or
hypopygium is more or less oval and tumid, its long axis lying in the
antero-posterior direction, with a vulviform median groove (the anus)
running from the anterior margin to beyond the middle.
[423] This does not include _G. maculata_, Newstead, which is regarded
by Austen as a synonym of _G. palpalis_, Rob. Des.; according to this
authority the curiously spotted appearance of the type and only example
of _G. maculata_ is due to foreign matter.
[Newstead has shown the importance of the study of the genitalia
in separating species (_vide_ _Bull. Ent. Res._, ii, pp. 9–36 and
107–110, and iii, pp. 355–360; and _Ann. Trop. Med. and Par._, vii,
No. 2, pp. 331–334).
[Illustration: FIG. 417.--Head of _Glossina longipalpis_, Wied.
(After Grünberg.)]
[Illustration: FIG. 418.--Antenna of _Glossina pallidipes_, male.
(After Austen.)]
[The tsetse-flies reproduce differently from all other _Muscidæ_. The
female produces at each birth a single full-grown larva, which is
retained within the oviduct and there nourished by the secretion of
special glands, and on being born crawls to some hiding place and at
once becomes a puparium.
[The larva is a yellowish footless maggot nearly as large as the
mother’s body, the skin shagreened and the anal extremity having a
pair of large, black, granular prominences separated by a depression
containing the breathing pores.
[The puparium is brown of various shades, the tumid lips of the
larva being conspicuous, the size and shape of the lips enabling the
puparia to be identified.
[These puparia are often found in masses at the base of trees,
in hollows in trees and rocks just buried under vegetal debris.
These insects are generally confined to definite tracts known as
“fly-belts.” They usually occur in damp, hot places on the borders
of rivers and lakes, and never far from water in the case of the
_palpalis_ group, although others of the _morsitans_ group may be
found a considerable distance from water. They are usually absent
on grass plains, but may now and then occur there (Kinghorn, _vide_
Hindles’ “Flies and Disease, Blood-sucking Flies,” 1914, p. 274);
cover of trees, shrubs, or thick reeds is essential to them.
[Their range in Africa extends roughly from 18° N. to 31° S.
[_Glossina palpalis_ is the chief carrier of the more prevalent type
of sleeping sickness. Two distinct types of parasites can produce
this disease, _viz._, _Trypanosoma gambiense_, which produces the
ordinary sleeping sickness, transmitted by _G. palpalis_, and
_Trypanosoma rhodesiense_ the Rhodesian or Nyasaland sleeping
sickness, transmitted by _G. morsitans_, and possibly identical with
_T. brucei_, the parasite of N’agana. Koch has also shown that _G.
pallidipes_, Austen, and _G. fusca_, Walker, can be artificially
infected with the human trypanosome. It appears probable that
Koch used _G. brevipalpis_, not _G. fusca_, in his transmission
experiments, as at that time fusca included nearly all the large
tsetses, but _brevipalpis_ is its Eastern representative.
[A TABLE OF SPECIES (modified after Austen) is appended here:--
I.
_Glossina palpalis_ GROUP.
1. Dorsum of abdomen ochraceous buff or buff;
third and following segments exhibiting
sharply defined, dark brown or clove brown,
interrupted transverse bands _tachinoides_, Westwood.
Dorsum of abdomen not so marked 2.
2. Third joint of antennæ pale (cream buff to
ochraceous buff), clothed with long and
fine hair, forming a conspicuous fringe on
front and hind margins _pallicera_, Bigot.
Third joint of antennæ entirely dark
(mouse-grey) except at extreme base on
outer side, and without a conspicuous
fringe of long and fine hair 3.
3. Dorsal surface of abdomen dark sepia brown;
median paler area on second segment broad,
and more or less quadrate or irregular in
outline; hypopygium of ♂ buff or ochraceous
buff _caliginea_, Austen.
Dorsal surface of abdomen blackish-brown;
median paler area cuneate (i.e., triangular
in outline); hypopygium of ♂ grey _palpalis_, Rob. Desv.
II.
_Glossina morsitans_ GROUP.
1. Hind tarsi entirely dark; small slender
species; abdomen bright ochreous or reddish
ochreous with dark lateral markings _austenii_, Newstead.
Hind tarsi not entirely dark; abdomen drab-
grey, buff or ochreous buff with conspicu-
ous dark interrupted transverse bands 2.
2. Last two joints of front and middle tarsi
with sharply defined clove brown or black
tips 3.
Last two joints of front and middle tarsi
without sharply defined clove brown or black
tips (front and middle tarsi either entirely
pale or, at most, two joints of front tarsi
faintly brownish at the tips), and last
joint and distal half of penultimate joint
of middle tarsi light brown, never so dark
as to form a sharp contrast with the
remaining joints _pallidipes_, Austen.
3. Third joint of antennæ with a distinct fringe
of fine hair on front margin; dark brown or
clove-brown bands on abdominal segments
extending close to hind margins (_i.e._,
pale ground colour, apart from the median
interspace, confined to a very narrow hind
border) _longipalpis_, Wiedeman.
Third joint of antennæ without a distinct
fringe of fine hair on front margin; dark
brown or clove-brown bands on abdominal
segments not extending close to hind margins _morsitans_, Westwood.
III.
_Glossina fusca_ GROUP.
1. Third joint of antennæ fringed with fine hair
on anterior and posterior margins; fringe on
anterior margin conspicuous under a hand
lens magnifying 15 diameters (nominal)
when head is viewed in profile 2.
Third joint of antennæ with fringe of fine
hair on anterior margin so short as to be
scarcely noticeable under a hand lens magni-
fying 15 diameters (nominal) when head is
viewed in profile (longest hairs in fringe
in length not exceeding one-sixth of width
of third joint); palpi long and slender 3.
2. Longest hairs in fringe on front margin of
third joint of antennæ, in length equal to
from one-fourth to one-third (not exceeding
one-third) of width of third joint; palpi
of moderate length _tabaniformis_, Westwood.
Longest hairs in fringe on front margin of
third joint of antennæ in length equal to
from one-half to three-fourths of width of
third joint; palpi noticeably long and
slender _nigrofusca_, Newstead.
3. Pleuræ drab-grey or isabella-coloured, hind
coxæ buff or greyish-buff _fusca_, Walker.
Pleuræ dark grey; hind coxæ mouse-grey _fuscipleuris_, Austen.
IV.
_Glossina brevipalpis_ GROUP.
1. Dorsum of thorax with four sharply defined
brown, more or less oval or elongate spots,
arranged in a parallelogram, two in front
and two behind the transverse suture;
proboscis bulb with a sharply defined brown
or dark brown tip _longipennis_, Corti.
Dorsum of thorax without such spots;
proboscis bulb not brown or dark brown at
tip 2.
Wings with upper thickened portion of anterior
transverse vein much darker in colour than
adjacent veins and thus standing out con-
spicuously against the rest of the wing _brevipalpis_, Newstead.
Wings with upper, thickened portion of
anterior transverse vein not much darker
in colour than adjacent veins, and thus
not standing out conspicuously against the
rest of the wings (wings practically
unicolorous) _medicorum_, Austen.[424]
[424] Newstead has recently described another species as _G. severini_
(_Ann. Trop. Med. and Par._, 1913, vii, No. 2, pp. 331–334). It is
allied to _G. fuscipleuris_, Austen.
*Glossina palpalis*, Rob. Desv.
[This is the chief carrier of sleeping sickness in Nature. It
is found in places over the whole of West Africa from the mouth
of the Senegal River to Angola, and extends eastwards into the
Bahr-el-Ghazal. The eastern boundary follows the valley of the Nile
and includes the eastern shores of Lakes Victoria and Tanganyika;
from the southern end of the lake the boundary tends south-west,
approximately following the frontier between North-eastern Rhodesia
and the Congo Free State, and passing through the Katanga district
of the latter country into Angola (Austen). It may occur up to
3,000 ft.; but, according to Bagshawe, it has not been recorded above
4,000 ft. It feeds on the blood of many animals, including reptiles,
amphibia, birds, and even amphibious fishes, as well as all the wild
mammals. It seems, however, to possess a decided predilection for
man, and undoubtedly thrives better upon mammals and birds than upon
cold-blooded animals.
[It is not usually found far from water, requiring a humid atmosphere
and temperature of about 85° F. (shade). But a marked seasonal
distribution is shown, the flies considerably extending their range
during the rainy season, and thus visiting districts which are
dry for the greater part of the year; as the rains diminish the
fly gradually leaves the temporary haunts and returns to the more
permanent ones. It bites only by day, and then only in sunny weather,
and usually lives in shade.
[Illustration: FIG. 419.--_Glossina palpalis_ and puparium. (After
Brumpt.)]
[Roubaud has shown that the first larva produced is about three
weeks after copulation, and that others are produced at an interval
of nine or ten days. The puparium stage is rapidly produced after
the expulsion of the larva, often in three-quarters of an hour. The
puparium stage lasts from thirty-two to thirty-five days. The puparia
occur in well-drained humus close to water, sheltered by trees or
bushes, in crevices in rocks, and between the exposed roots of trees,
sometimes in sand.
[Bruce has shown that only a very small percentage of flies fed
experimentally on infected animals ultimately become infective, and
that the infectivity of this small percentage depends upon a delayed
infection of the salivary glands.
[A variety, _wellmani_ of Austen, is found in Angola, Gambia, the
Katanga district of the Congo Free State, the Matondwi Islands of
Tanganyika, etc.
*Glossina morsitans*, Westwood.
[This species has been shown by Kinghorn and Yorke, and also by
Bruce, to be responsible for the transmission of _Trypanosoma
rhodesiense_, the micro-organism producing sleeping sickness in man
in Rhodesia and Nyasaland and also in parts of German and Portuguese
East Africa. Fisher and Taute have demonstrated experimentally
that _Trypanosoma gambiense_--the sleeping sickness parasite of
other parts of Africa--may also be transmitted by this fly, and in
addition it is known to be capable of disseminating several species
of trypanosomes pathogenic to animals. Of these, _T. brucei_ (=? _T.
rhodesiense_), the parasite of tsetse disease, first incriminated by
Bruce, is perhaps the most important.
[Illustration: FIG. 420.--The tsetse-fly (_Glossina morsitans_,
Westwood).]
[It is the most widely spread of all tsetse-flies; its range
extends from Senegambia in the north-west to Southern Kordofan and
Southern Abyssinia in the north-east, and then southwards to the
Bechuanaland Protectorate, North-eastern Transvaal and Zululand. The
actual localities given by Austen are Gambia, French Guinea, Gold
Coast, Togoland, Dahomey, Northern Nigeria, Congo Free State, the
Bahr-el-Ghazal, the Uganda Protectorate, German East Africa, and
Portuguese East Africa.
[This species is confined to “belts,” often of very limited extent,
and appears to prefer regions where there is sufficient vegetation
for moderate but not excessive cover and a hot, moderately dry
climate. It is not nearly so dependent upon water as is _G.
palpalis_, and generally is most active in a dry atmosphere; some
observers, however, state that in certain districts it is more common
along the banks and edges of rivers. This tsetse-fly has been taken
as high as 5,500 ft. altitude. It infests native villages as well
as the bush. Like other tsetse-flies it bites not only during the
hottest part of the day, but also on bright warm moonlight nights,
and it feeds on the blood of all mammals.
[The structure of the male genitalia of those representatives of _G.
morsitans_ occurring on the West Coast of Africa and in parts of the
Soudan presents certain constant differences from that of the typical
form of this species; this form is known as _G. morsitans_, race
_submorsitans_, Newst.
Genus. *Stomoxys*, Geoffroy.
[The members of this genus which occur in temperate and tropical
countries are provided with a hard, slender, shiny black proboscis
which projects horizontally from beneath the head; by means of this
structure they can bite severely. In general appearance they resemble
house flies, but the proboscis at once distinguishes them. In many
parts of Britain they are known as storm flies on account of their
frequent appearance indoors previous to a storm of rain or wind,
which I have invariably found to be correct; they are also called
stinging flies. In colour they are greyish, dusky or brownish-grey
or black, varying from 5 to 7 mm. in length; the thorax has dark
longitudinal stripes and the abdomen dark spots or bands. In the male
the eyes are closer together than in the female. These flies usually
occur in stables and farmyards, along woods and in lanes, and mainly
attack mammals.
[Illustration: FIG. 421.--The stinging fly (_Stomoxys calcitrans_,
Linn.).]
[One species (_Stomoxys calcitrans_, Linnæus) occurs practically all
over the world. The female lays her eggs in moist, warm, decaying
vegetation; as many as eighty may be laid by a single female. The
ova are white, banana-shaped, with a broad groove on the shorter
curvature; they may hatch in two or three days. The creamy-white
larva tapers to a point at the head end, and is truncated at the
tail end. Two black mouth hooks are plainly visible at the cephalic
extremity. There are two plates on the posterior surface of the last
segment which bear the respiratory pores, nearly circular in outline.
It reaches maturity in fourteen to twenty-one days; when mature it
is 11 mm. long. The pupal stage is passed in the old larva skin and
lasts from nine to thirteen days; it is barrel-shaped, 5 to 8 mm.
long, and of a bright reddish-brown to dark chestnut-brown colour.
[This insect may act as a carrier of anthrax, and has been proved to
be the agent of an extensive epidemic of malignant pustule in the
Isle of Pines, New Caledonia.[425]
[425] _Bull. des Séances de la Soc. ent. de France_, 1878, pp. cxliv,
cxlv.
[Noè’s[426] experiments tend to show that it is an intermediate host
and transmitter of _Filaria labiato-papillosa_ of the ox.
[426] _Atti della Reale Accad. dei Lincei, Anno CCC. Se Quinta_, 1903,
xii, 2 sem. fasc., pp. 387–393.
[Surra is generally stated to be transmitted by Stomoxys as well
as Tabanus, and yet Nitzman in the Philippines obtained uniformly
negative results in exhaustive experiments. Others have also been
unsuccessful. Certainly Stomoxys can transmit the disease in French
West Africa (Bonet and Roubaud), and mechanically has been proved
to be capable of disseminating other trypanosomes (experimentally):
sleeping sickness (_T. gambiense_); nagana (_T. brucei_); souma (_T.
cazalboui_); and el debat (_T. soudanense_).
[_S. calcitrans_ may also be a carrier of poliomyelitis (Rosenau and
Brues, _Harvard Alumni Bulletin_, 1912, xv, No. 9, pp. 140–142).
Several species are now known (_S. brunnipes_, Grünb.; _S. inornata_,
Grünb.; _S. nigra_, Macq.; _S. omega_, Newst.; _S. ochrosoma_,
Speiser, etc.).
Genus. *Lyperosia*, Rondani.
[A genus of small flies which bite man and animals, but are not so
far connected with the transmission of any disease in man, but in
Java it appears to carry surra (P. Schat, _Meeledeel Praefstation
Oost-Java_, 1903, 3e ser., No. 44), the species being _Lyperosia
exigua_, Meijere. These flies can be told from Stomoxys by the palpi
being broader, flattened laterally, and as long, or nearly so, as the
proboscis. When not feeding the palpi enclose the proboscis, as in
Glossina. They are usually about half the size of Stomoxys, and are
the smallest blood-sucking _Muscidæ_. They frequently swarm around
and upon domesticated animals.
[The life-history of the horn fly in America (_L. irritans_, Linn.)
is well known. It lays its ova singly in freshly dropped cow-dung,
and there the maggots feed, pupating in the soil beneath.
[Patton and Cragg also give some details as to the life-history of
_Liperosia exigua_ (“Medical Entomology,” p. 375) as follows: “_L.
exigua_, whose habits have been observed in Madras, usually lays
twelve eggs at a time. The flies immediately return to the cow and
the process is repeated when the dung is again dropped. The larvæ
migrate from the dung when about to pupate, and the puparia are
always found in the earth at some distance away or under the sides of
the patch of dung. The fly usually hatches out in five days, though
sometimes as late as the eighth. Weiss has studied the life-history
of _irritans_ var. _weisii_ from Algeria; its larval stage lasts five
days, and the flies hatch out of the puparia in another five days.”
[The other biting genera of _Muscidæ_, Hæmatobia, Hæmatobosca,
Bdellolarynx, Stygeromyia, and Philæmatomyia, although sometimes
annoying to man, have not in any way been connected with any disease.
[The horse fly (_Hæmatobia irritans_, L.[427]) attacks cattle
chiefly, but now and then man is bitten. The different species can be
told from Stomoxys by the palpi being nearly as long as the proboscis.
[427] This is apparently the _stimulans_ of Meigen.
[The genus *Philæmatomyia*, Austen, is intermediate between Stomoxys
and Musca in structure, and between the non-blood-sucking Musca, as
_M. domestica_, and the blood-sucking _Musca pattoni_, Austen, which
feeds on the blood exuding from the bites of true blood-suckers. They
occur in Central Africa and India, Ceylon and Cyprus (_vide_ “The
Life-history of _Philæmatomyia insignis_, Austen,” _Ann. Trop. Med.
and Par._, 1912, v, p. 515).
[Two flies belonging to the family *Anthomyidæ* also attack man,
namely:--
[_Hydrotæa meteorica_, L. (the meteoric fly). This fly attacks man as
well as animals. They especially bite around the eyes and nostrils
of animals, but are not so particular with man; the head, however,
is usually chosen. Linnæus called it the meteoric fly because it
often forms clouds around horses’ heads at the approach of rain. The
Hydrotæas are usually black or blue-black in colour with bare eyes
and simple abdomen, the front femora peculiarly constructed. _H.
meteorica_, L., occurs in Britain.
[The members of the genus Hydrophoria, Desvoidy, also bite man.
*Pupipara* or *Eproboscidæ*.
[The _Pupipara_ are all blood-suckers, the majority occurring as
parasites on mammals and birds, where they are more or less permanent
parasites. Occasionally some may attack man. They all produce their
young fully formed, and they assume the pupal stage immediately
after extrusion. The puparia are large. They are mostly flat,
louse-like flies which may or may not be winged. In the case of
Melophagus I have found the puparia are often passed by the female.
The winged forms have a short quick flight, and when disturbed will
seek shelter in man’s hair or beard. Two main families occur: (1)
the _Hippoboscidæ_, and (2) the _Nycteribiidæ_. The former occur on
animals and birds, the latter on bats only, but may invade man. Two
other families are known--the _Braulidæ_ (bee parasites) and the
_Streblidæ_ (bat parasites).
[The mouth of the _Hippoboscidæ_ is long and sharp, forming a
proboscis. The thorax and abdomen are flat and leathery. The legs
are stout and strong, and terminate in large dentate claws and other
structures of use in holding on to the hair or feathers of their host
when blood-sucking.
[Austen says it is probable that the _Hippoboscidæ_ are descended
from ancestors belonging to the _Muscidæ_, which underwent
modification in bodily structure as the consequence of the adoption
of a parasitic mode of life.
[Two wings are present in the true Hippoboscæ, _Hippobosca equina_
(of the horse), _H. camelina_ (of the camel), _H. maculata_ (of
oxen), and _H. capensis_ (of dogs), but are absent in Melophagus, the
sheep tick or ked fly (_M. ovinus_).
[In two genera, Lipoptena and Echestypus, wings are at first present,
but are lost as soon as the fly finds its permanent host.
[With regard to their biting man, such is only occasional. I have
known sheep shearers to be badly bitten by _Melophagus ovinus_, and
have more than once been attacked myself when standing where shearing
is taking place. Sharp records the grouse parasite, _Ornithomyia
lagopodis_, as once biting severely a gamekeeper in Scotland. There
are also records of _H. maculata_ biting man in Africa and India.
[Although so far not connected with any human disease, it is
interesting to note Theiler has shown that _Hippobosca rufipes_,
v. Olfers, and _H. maculata_, Leach, are capable of transmitting
_Trypanosoma theileri_, Laveran, the cause of gall sickness amongst
cattle in the Transvaal. It is now considered, however, that
_Trypanosoma theileri_ is non-pathogenic, and that the cause of
gall sickness is a piroplasma-like organism known as _Anaplasma
marginale_. Theiler, Laveran and Mesnil all hold this view (_vide_
Laveran and Mesnil, “Trypanosomes and Trypanosomiases,” second
edition, 1912, p. 330).
[_Lynchia._--Three members of this genus have been shown to transmit
the non-pathogenic (?) organism, _Hæmoproteus columbæ_ amongst
pigeons in Algeria and S. America.
Insects and Epidemic Poliomyelitis.
[In a recent number of the _Journal of Economic Entomology_,[428]
Brues and Sheppard point out the possibility of acute epidemic
poliomyelitis (infantile paralysis) being an insect-borne disease.
They summarize as follows:--
[428] Charles T. Brues and Philip A. E. Sheppard, “The Possible
Etiological Relation of certain Biting Insects to the Spread of
Infantile Paralysis,” _Journ. Econ. Ent._, 1912, cciv, pp. 305–324.
[Many facts connected with the distribution of cases and the spread
of epidemics of this disease with histories of insects bites, suggest
at least that the disease may be insect-borne. Field work during
the past summer, together with a consideration of the epidemiology
of the disease so far known, points strongly towards biting flies
as possible carriers of the virus. It seems probable that the
common stable fly (_Stomoxys calcitrans_, L.) may be responsible to
a certain extent for the spread of acute epidemic poliomyelitis,
possibly aided by other biting flies such as _Tabanus lineola_. No
facts which disprove such a hypothesis have as yet been adduced, and
experiments based upon it are now in progress.
[If the disease should prove to be common to any species of domestic
animals, as is now strongly suspected, a secondary connection of
ticks in spreading the disease among such animals seems probable, as
has been mentioned.
[The following is some of the more important literature on
_Diptera_ in general: Meigen, J. W., “Syst. Besch. d. bek. europ.
zweiflügligen insecten,” 1818–1838, 7 vols.; Brauer, F., “Monographie
der Oestriden,” Wien, 1863; _Idem_, “Nachtr. hiersu,” _Wien. ent.
Zeit._, 1887, vi, pp. 4, 71; Schiner, J. R., “Fauna austriaca: die
Fliegen,” Wien, 1860–64; Löw, Fr., “Ueber Myiasis und ihre Erzeuger,”
_Wien. med. Wochenschr._, 1882, xxii, p. 247; 1883, xxxiii, p. 972;
Joseph, G., “Ueb. Fliegen als Schädlinge und Parasiten des Menschen,”
_Deutsch. med. Zeit._, 1885, i, p. 37; 1887, iii, pp. 713 and 725;
Peiper, E., “Fliegenlarven als gelegentl. Paras. d. Mensch.,” Berlin,
1900; Theobald, F. V., “Monograph of the Culicidæ of the World,”
1901–1911, 5 vols. and 1 atlas, plates; Austen, E., “A Monograph
of Glossina Tsetse-flies,” 1903, 1 vol.; Van der Wulp, “Diptera
neerlandica,” 1877; Walker, “Insecta Britannica: Diptera,” 1851–53
and 1856; Lundbeck, “Diptera danica,” 1907–12; Zetterstedt, “Diptera
scandinaviæ,” 1850; Theobald, “British Flies,” 1892; Aldrich, “N.
American Diptera,” 1905; Loew and Osten Sacken, “Monographs of the N.
American Diptera,” 1862–63 and 1869; Macquart, “Diptera exotique,”
1830–47; Rondani, “Diptera exotica et Italica,” 1863–68; Williston,
“Manual of Families and Genera of N. American Diptera,” second
edition; Verrall, “British Flies.” A fuller literature will be found
in Peiper, as well as in Huber’s “Bibliographie d. klin. Ent.,” 1899,
iii, Jena, in the Bibliography at the end of this work and in the
_Rev. of App. Ent._ (Dulau and Co., London), where all references to
modern research can be found.--F. V. T.]
ADDENDA.
*Akamushi or Kedani Sickness* (_vide_ also p. 487).--Schuffner (Far
East. Assoc. Trop. Med., _Compt. rend. Trois. Cong. Biennial_, 1913,
Saigon, 1914, pp. 309–315) states he observed a peculiar fever in
Deli, Sumatra, somewhat resembling typhoid. This he traced either to a
mite or tick. He figures the possible carriers, namely, a Trombidium
and _Cheyletidæ_. He calls this disease pseudo-typhus--a variant
of Japanese kedani sickness, which, he says, also occurs in the
Philippines.
*Ticks.*--AFRICAN TICK FEVER: Marzinovsky (_Proc. of Conference of
Bacteriologists and Representatives of Medical Sanitary Authorities
on the Campaign against Infectious Diseases in connection with the
War, Soc. Russ. Physicians in mem. Pirosov_, Moscow, 1915, pp. 56–68),
states that African tick fever has been imported into Persia, and that
it is there carried by _Ornithodorus tholosani_.
TICK PARALYSIS: Todd (“Paralysis and Tick-bite,” _Can. Med. Assoc.
Journ._, 1914, iv, No. 9, pp. 825–826) refers to paralysis ascribed
to the bites of ticks in children, and possibly adults, in America,
British Columbia and Australia. He states that a young child, perfectly
well one day, has more or less complete paresis or paralysis on the
next, fever, a rapid pulse, and other constitutional symptoms. The
child may be dull and stupid, and may have convulsions. If the tick
is not found and removed the child may die, but if it is removed, the
symptoms disappear and recovery is complete in a few hours. The tick
must be entirely removed.
*Diptera.*--PSYCHODIDÆ: Bolt (_China Med. Journ._, Shanghai, xxix, No.
2, pp. 78–86) states that sand-flies (Plebotomus) and the fever due to
them are common in North China, May and June being the worst months.
The natives of the region appear to be immune, but all others suffer.
Old ruined buildings are the favourite haunts of the Phlebotomus. The
species of Phlebotomus has not been determined.
*Pulicidæ.*--DERMATOPHILUS (SARCOPSYLLA) PENETRANS, OR THE
“JIGGER.”--This flea (_vide_ p. 544) is believed by Lama (_Giorn. Ital.
Mal. Ven._, Milan, 1914, xlix, pp. 465–472) frequently to carry leprosy
and he points out that the early lesions of leprosy usually appear on
the uncovered parts of the body. This flea also attacks rats.
*Brachycera.*--LEPTIDÆ (_vide_ p. 603): White, A. (“The
_Diptera-Brachycera_ of Tasmania,” part I, _Papers and Proc. Roy. Soc.
of Tasmania_ for 1914, 1915, pp. 35–74), describes a new blood-sucking
Leptid, _Spaniopsis tabaniformis_, which resembles a small gad fly
(Tabanus) in appearance.
_Pycnosoma putorium_: This is believed by Roubaud (“Les Producteurs de
Myiases et Agents similaires chez l’homme et les animaux,” Paris, 1914,
part I) to be largely concerned in the spread of amœbic dysentery in
French West Africa.
_Lucilia argyrocephala_, Macquart: This green-bottle fly is described
by Roubaud as producing myiasis in Africa (“Les Producteurs de Myiases
et Agents similaires chez l’homme et les animaux,” 1914, Paris, part
I). It attacks ulcers and sores in man and animals.
_Auchmeromyia luteola_, Fabr.: Schwetz (_Ann. Trop. Med. and Par._,
1914, viii, No. 3, pp. 497–507), collected a large quantity of this
insect at Kabinda. He placed them in flasks with sand and a few days
later they pupated, and in fifteen days several flies hatched out. The
larval period varies from an unknown minimum up to several months.
The larva may live for at least two months without food. A female
oviposited on the 17th, and on the 18th one larva hatched. The pupal
stage seems to last eight to fifteen days. The larvæ appear to bite by
day as well as night according to native information.
_Cordylobia anthropophaga_, Grünb.: Roubaud (“Etudes sur la Faune
parasitaire de l’Afrique occidentale française,” part I, “Les
Producteurs des Myiases et Agents similaires chez l’homme et les
animaux,” Paris, 1914) gives the life-history of this species. One
fly laid 150 ova in a glass vessel, on the sides, and on some rotten
fruit, and died the following day. He found that fifteen larvæ just
hatched placed on sand in a glass vessel with a guinea-pig gave rise
to characteristic tumours on the ventral surface of the body and the
anus. Other experiments failed. It thus seems that infection takes
place from larvæ which have hatched apart from the host. Infection of
man is regarded as accidental; no positive infection of horses, oxen,
sheep or pigs is known--it is rare in goats, and poultry never seem to
be attacked. The result of experiments tends to show that the apparent
choice of a host is mainly a question of body temperature. The larva,
whether freshly emerged or eight to ten days old, penetrates the skin
immediately, boring obliquely between the epidermis and dermis. Once
removed from the tumour the maggot cannot bore again. The first moult
takes place about three days after penetration, and the total period of
residence in the host is seven to eight days. Upon emerging the larva
falls to the ground and buries itself. In two or three days it pupates
and this stage lasts no longer than twenty days. High temperatures,
such as 95° F., appear to be fatal.
*Myiasis.*--Coates, G. M., “A Case of Myiasis Aurium accompanying the
Radical Mastoid Operation,” _Journ. Amer. Med. Assoc._, Chicago, Ill.,
1914, lxiii, pp. 479–480: Apparently _C. macellaria_, forty to fifty
coming away with the gauze after the operation.
Huber, G. U., and Flack, F. L., “An Unusual Case of Screw-worms in the
Nose and Nasal Accessory Sinuses,” _Journ. Amer. Med. Assoc._, Chicago,
1914, lxiii, pp. 2288–2289.
*Auricular Myiasis.*--Francaviglia, M. C., “An cora sulla myiasi
auricolare,” _Boll. Sedute Accad. Gioenia_, Catania, 1914, No. 31, pp.
15–23. This writer mentions the following parasites in the human ear:
_Sarcophaga carnaría_, L.; _Wohlfartia magnifica_, Schiner; _Chrysomyia
macellaria_, F.; _Calliphora vomitoria_, L.; and _Anthomyia pluvialis_,
L. He refers to a severe myiasis in Russia, due to a fly variously
recorded as _Sarcophaga wohlfarti_, Rond.; _S. ruralis_, Meig.; or
_Sarcophila meigeni_, Portsch. These are all probably synonyms of _W.
magnifica_. _Chrysomyia macellaria_, in Central America and South
America, is quite as harmful as _S. carnaria_, causing perforation of
the tympanum and meningitis. _Lucilia nobilis_ and _L. cæsar_ have also
been incriminated. Of the sub-family _Anthomyinæ_, the larvæ of _Fannia
scalaris_, Meig., _F. canicularis_, Meig., _F. incisurata_, Zett, and
_Hydrotæa meteorica_, L., are chiefly associated with myiasis. He
recommends, if the larvæ are outside the tympanum, an injection of
chloroform vapour by a few drops of water saturated with chloroform,
by an emulsion of 5 per cent. carbon bisulphide or with benzine. When
detached they may be removed with forceps or a solution of boric acid.
If the tympanum has been perforated, the larvæ must be removed at once.
Francaviglia also records the larva of _Oestrus ovis_ in the human ear
(_Boll. Sedute Accad. Gioenia_, Catania, 1914, No. 31, pp. 23–27).
*Body, Head, and Clothes Lice.*--Lobaczewski (_Wien. klin.
Wochenschr._, Vienna, 1915, xxviii, pp. 373–374) recommends the
impregnation of body linen with a 30 per cent. solution of oleum betæ
in 96 per cent. alcohol as an efficient method of keeping the body free
of lice. But the process must be renewed each time the linen is washed
and it takes fifteen minutes to carry out. On adding the oil to the
alcohol, a portion of the former is precipitated, the supernatant fluid
is decanted and poured over the linen, which is wrung out in it and
dried. The garments retain their lice-proof properties until washed.
Three days after wearing the clothes thus treated no lice remain on the
body.
Portnikov, _Proc. of Conference of Bacteriologists and Representatives
of Medical Sanitary Authorities on the Campaign against Infectious
Diseases in connection with the War, Soc. Russ. Physicians in mem.
Pirosov_, Moscow, 1915, p. 131.
_Pediculus capitis_ and _Phthirus pubis_ are shown to be successfully
controlled by applying spirit extract of sabadilla and both white and
grey mercury ointment, solution of corrosive sublimate of a strength
of 1 in 250 to 1 in 100, amyl and ethyl alcohol, benzine, chloroform,
carbon tetrachloride, methane, birch tar, liquid of malinin, etc. The
control of _Pediculus vestimenti_ by the mixture of tartaric acid and
sodium sulphite slightly moistened with water is advised. It is placed
in small linen bags underneath the shirt; the heat of the body produces
a reaction which continues for two days, giving off a large amount of
SO_{2}, which spreads beneath the shirt and kills all the parasites
but does not affect the skin. Marzinovsky, in the same _Proceedings_
(pp. 56–68), gives a number of remedies for _Pediculus vestimenti_
(called _humanus_), and mentions quinine or mercury, which latter
the natives in Turkestan carry on their hands and legs in bracelets
soaked in mercury compounds. He also mentions ethereal oils, the most
effective being clove oil, eucalyptus, oil of anise and camphor. He
recommends for disinfecting clothing for army purposes the chamber
used by the Japanese on a large scale. Kummerfelds’ wash is advised,
and is prepared as follows: 20 parts of precipitated sulphur are
incorporated in a mortar with 50 parts of glycerine; 2 parts of camphor
are separately ground with 50 of eau-de-Cologne and 20 of borax, and
870 parts of distilled water are added; the whole is mixed together and
3 drops of an extract of musk are added; shake in order to prevent the
sulphur settling down; 50 parts of ether are added to the mixture. This
sounds an expensive and troublesome preparation to make.
Shipley A. E., “Flowers of Sulphur and Lice,” _Brit. Med. Journ._,
1915, p. 295. It is here stated by Dr. Lounsbury that the South
African troops were supplied by the Government with bags of flowers
of sulphur sewn in small calico bags and secured to the underclothing
next the skin as a preventive of lice. The bags were 2 in. square, one
on the trunk and one against each leg. This is a generally accepted
preventive, but is best mixed with equal parts of creosote and
naphthalene.
Shipley, A. E., “Insects and War,” _Brit. Med. Journ._, September 19 to
November 14, 1914. General advice given _re_ lice.
SUPPLEMENT:
CLINICAL AND THERAPEUTICAL NOTES.
PROTOZOA.
INTRODUCTION.
The aim of the present volume is to give an account of the animal
parasites of man, the number of which is very large. The Protozoa that
infest man are very important, and the literature relating to them and
to the treatment of the diseases that they produce is very extensive.
All that can be done in this Appendix is to give a very brief outline
of some of the more recent and approved methods of treatment, for
further details of which the reader should refer to standard medical
works, among which the following are noteworthy:--
Allbutt and Rolleston (1907): “System of Medicine,” vol. ii, part 2,
“Tropical Diseases and Animal Parasites,” London.
Castellani and Chalmers (1913): “Manual of Tropical Medicine” (second
edition), London.
Laveran and Mesnil (1912): “Trypanosomes et Trypanosomiases” (second
edition), Paris.
Manson (1914): “Tropical Diseases” (fifth edition), London.
Mense (1905): “Handbuch der Tropenkrankheiten,” Leipzig.
Ross (1911): “The Prevention of Malaria,” London.
Scheube (1910): “Die Krankheiten der Warmen Länder,” Jena.
References to the treatments tried in many parasitic diseases can be
found in the _Sleeping Sickness Bulletin_ and _Kala-azar Bulletin_,
both now superseded and greatly extended in scope in the _Tropical
Diseases Bulletin_, published by the Tropical Diseases Bureau, Imperial
Institute, London, S.W.
The following diseases, due to protozoa and allied forms, are
discussed:--
I. Amœbic Dysentery.
II. Trypanosomiases.
III. Flagellate Diarrhœa and Dysentery.
IV. Leishmaniases--Kala-azar and Oriental Sore.
V. Spirochætoses--Relapsing Fevers, Yaws, Syphilis and Bronchial.
VI. Malaria.
VII. Balantidian or Ciliate Dysentery.
I.--AMŒBIC DYSENTERY.
Amœbic dysentery, due to _Entamœba histolytica_ (see pp. 34–41), is
present throughout the tropical world and also occurs in temperate
zones.
Walker and Sellards[429] (1913) conducted important experiments
with amœbæ on prisoners in the Philippine Islands. They showed
experimentally that cultural amœbæ are non-pathogenic. As regards
experiments with _Entamœba coli_, after feeding to twenty individuals
they concluded that _E. coli_ is a parasite of the human intestine but
non-pathogenic and non-culturable. In a third series of experiments,
after feeding with motile _Entamœba histolytica_, tetragena cysts were
found in the stools later; when tetragena cysts were administered,
motile _E. histolytica_ were present in the subsequent stools. Some
of the histolytica cases developed dysentery after a time. They lay
stress on the necessity for the frequent examination of stools in order
to detect carriers. The incubation period of entamœbic dysentery is
usually long.
[429] _Philippine Journ. Sc._, B, viii, p. 253.
With regard to the symptomatology of amœbic dysentery, Castellani and
Chalmers distinguish four types--the acute, chronic, latent, and mixed
types.
The acute type has an abrupt onset; pain is felt in the lower part
of the abdomen, and the motions, rarely exceeding thirty daily,
are accompanied by much griping and straining. Blood and mucus are
present in the motions, and occasionally greyish material, consisting
of leucocytes, mucus, Charcot-Leyden crystals, amœbæ, and bacteria,
sometimes with particles of tissue. Nausea and vomiting may occur.
Digestion is usually deranged. The abdomen is sunken, the liver and
spleen are normal, but tenderness is felt along the course of the large
intestine. The urine may be diminished in quantity.
The chronic type may succeed the acute, or appear like diarrhœa, the
motions being fæculent and containing mucus. Between exacerbations,
constipation may occur. The number of motions may only be twelve to
fourteen per diem. Gangrenous complications may occur at any time, and
chronic dysentery may persist for many years.
The latent type is important, as the patients, though free from
dysenteric symptoms, harbour amœbæ and act as parasite carriers. The
latent condition may lead to acute attacks or to liver abscess.
The mixed type occurs where amœbic and bacillary dysentery are
combined. There is much fever, nausea, and vomiting. The motions are
numerous and often very offensive.
_Treatment._--The most modern method of treatment, due to Leonard
Rogers, is by emetine. According to Castellani and Chalmers, it is
well to relieve griping and straining by either a hypodermic injection
of morphia or by small enemata of 40 minims of laudanum in 1 oz. of
mucilage of starch or by using 1/4 gr. morphia or 1/4 gr. codeine
suppository. A dose of castor oil (ʒiv to ʒvi) with or without a few
minims of liquor opii sedativus or a few doses of saline may be given
during the first twenty-four hours. After the castor oil has acted or
simultaneously, emetine treatment should be commenced; 1/3 to 1/2 gr.
of emetine hydrochloride, dissolved in sterile normal salt solution, is
injected hypodermically three times a day for two or three days.
If emetine cannot be obtained, 5 gr. doses of ipecacuanha every three
to six hours in the form of membroids, or as pills coated with salol or
keratin, can be substituted.
After acute symptoms have disappeared, intestinal irrigations once or
twice daily, on alternate days, are useful. A solution of tannic acid
(3 to 5 per 1,000) or of quinine bihydrochloride varying in strength
from 1 in 5,000 to 1 in 750 is very slowly injected in quantities of
1/2 to 3 pints by means of a long, soft, rectal tube.
For gangrenous dysentery Castellani and Chalmers state that
appendicostomy, with irrigation of the whole lower bowel with quinine
lotion (1 in 1,000) or collargol (1 in 500), is the only chance.
The use of emetine should be continued in smaller doses after the
dysenteric symptoms have ceased, in order to prevent relapses and as a
possible safeguard against the development of a liver abscess.
Recently (July, 1914), Dr. W. E. Deeks[430] has given an account of
his successful procedure in dealing with the dysenteries in the Ancon
Hospital, Panama Canal Zone, of which medical clinic he is the chief.
With regard to amœbic dysentery he advocates: (1) Rest, to increase the
patient’s resistance; (2) a generous milk diet, which is practically
all absorbed before it reaches the large bowel; (3) saline or plain
water irrigations, one to three daily; (4) the administration of
bismuth sub-nitrate in heroic doses; 180 gr. is given mechanically
suspended in about a tumbler of plain or effervescent water every three
hours, day and night in severe cases, only lessening the amount when
improvement takes place. Mechanical suspension in a large quantity of
water is essential. When the stools begin to decrease in number and the
tongue becomes clean, the number of doses is reduced to three or four
daily. In very chronic cases one or two doses daily for a month after
convalescence are recommended.
[430] _Annals Trop. Med. and Parasitol._, viii, pp. 321, 353.
In exceptional cases of extreme emaciation and exhaustion, showing
marked toxic symptoms, surgical treatment is necessary, and at Ancon a
wide, open cæcostomy is performed.
The treatment of dysentery with bismuth sub-nitrate has been in use
for some years at Ancon. Latterly, a combined treatment by hypodermic
injections of emetine and bismuth sub-nitrate by the mouth has been
used, and the authorities there consider that it is better to combine
the two drugs rather than use each singly. Emetine probably acts as
a direct poison to the amœbæ, while the bismuth probably acts by
destroying the symbiotic organisms necessary for their growth.
With regard to preventive measures, all drinking water should be
filtered and boiled, and uncooked vegetables and salads avoided.
Scrupulous care with regard to personal cleanliness, and avoidance of
touching the mouth or lips after contact with dysenteric patients, are
essential. Isolation of parasite carriers is of great use in combating
and controlling outbreaks of amœbic dysentery. The pollution of soil
and water must be rigorously prevented.
Liver abscess due to amœbæ must be localized by exploratory
punctures, and then opened and drained. Intramuscular injections of
emetine hydrochloride, 1/6 gr. to 1/2 gr. every day, will reduce the
temperature and afford relief.
Oral endamœbiasis has been recently investigated by Bass and Johns,
Smith and Barrett and colleagues (see pp. 43, 733). It responds
to treatment with emetine, and 1/2 gr. of emetine hydrochloride
administered hypodermically each day is of service. Rinsing the mouth
with a solution of fluid extract of ipecacuanha is also useful.
Rogers[431] (1915) recommends a combined treatment of emetine and
streptococcal vaccines for pyorrhœa alveolaris.
[431] _Ind. Med. Gazette_, April, 1915, l, p. 121.
II.--TRYPANOSOMIASES.
The human trypanosomiases are those occurring in Africa, due to
_Trypanosoma gambiense_ and _T. rhodesiense_ and spread by Glossinæ,
and that due to _T. cruzi_, occurring in South America and spread
by the Reduviid bugs, _Triatoma_ spp. These trypanosomiases present
different clinical features and are best dealt with separately.
African Sleeping Sickness.
Sleeping sickness, due to _Trypanosoma gambiense_ or varieties thereof,
was first reported from West Africa and is now present, not only along
the West Coast and in Nigeria, but throughout the Congo basin into
Uganda, north of which it exists in the Bahr-el-Ghazal province of
the Sudan. In Nyasaland and Rhodesia a more virulent but less widely
distributed disease is produced by _Trypanosoma rhodesiense_.
There is a general similarity between the two diseases, and the
symptoms as described by the leading authorities agree in the main. The
malady due to _T. rhodesiense_ has been known only since 1910 and the
differences between the malady due to it and to _T. gambiense_ will be
indicated.
The course of the disease may be roughly divided into three stages, the
incubation, the febrile or glandular, and the cerebral stage.
The exact incubation period is not known with certainty in man.
Probably, in most cases, it does not exceed two to three weeks, but
disease signs may not appear for months. The bite of the Glossina gives
rise to local irritation, which may be overlooked. The irritation
usually subsides in the course of a few days.
The febrile, or glandular stage, is marked by attacks of fever of
an intermittent type. An erythematous eruption is often found on
Europeans. This rash begins as irregularly shaped pinkish patches which
clear in the centre until a ring is produced. It may occur on any part
of the body but is more frequent on the trunk. A typical symptom is the
enlargement of one or more of the lymphatic glands, especially those
of the neck. A general, deep hyperæsthesia, known as Kerandel’s sign,
may be present, and if the patient strikes a limb against any hard
object, a feeling of acute pain is felt, the sensation being slightly
delayed. As repeated attacks of fever increase, the patient may become
anæmic. The febrile stage may last for years, and cure may be brought
about at this phase, but frequently, after the febrile stage has
lasted some time, the cerebral stage is reached. Tachycardia is also
a symptom. Auto-agglutination of the red blood corpuscles is another
useful characteristic, as it is said to occur rarely in other tropical
diseases, but some workers doubt its value.
The cerebral, or true sleeping sickness stage is marked by a great
change in the habits of the victim, who becomes apathetic and dull,
careless and dirty in habits, and begins to experience difficulty in
walking. Tremors of varying degrees of severity are common and the
gait is peculiar. There is usually fever with rise of temperature from
100° F. to 104° F. in the evening, becoming subnormal in the morning.
For some days before death, it often becomes permanently subnormal.
Congestion and œdema of the lungs, with patches of pneumonia, are not
infrequently observed before death. The torpor gradually deepens, and
the patient loses flesh. Frequently the lips swell and saliva dribbles.
The patient usually becomes comatose and death ensues. Mania and
delusions, and psychical and physical symptoms resembling those found
in general paralysis of the insane, sometimes occur, and death may
arise from secondary complications such as pneumonia or dysentery.
Pathologically, the disease seems to consist of a chronic inflammation
of the lymphatic system. The trypanosomes reach the lymphatic glands
which become inflamed, and gradually invade the blood and the
cerebrospinal fluid. Sooner or later, as a result of the lymphatic
disease, changes occur in the membranes and substances of the brain
and spinal cord. There is round-celled perivascular infiltration of
the pia-arachnoid of the brain and spinal cord. These changes cause
compression of the blood-vessels, and so lessen the supply of blood to
the brain and spinal cord. Further changes in the latter organs result
in the production of the symptoms that have given the disease the name
of “sleeping sickness.”
The disease due to _Trypanosoma rhodesiense_ generally runs a more
rapid course than that due to _T. gambiense_. The torpor and sleepiness
may not be obvious or be very slight, and the enlargement of the
lymphatic glands of the neck also may not be marked or may appear to be
absent. The duration of the disease often appears to be from three to
six months.
Treatment is only of use if commenced in the earlier stages of the
disease. The substances of most value so far are arsenic in the form of
atoxyl (introduced by Wolferstan Thomas in 1905) and antimony in the
form of tartar emetic. Castellani and Chalmers and Manson recommend
treatment by combining the use of both substances. The combined
treatment is recommended not only because both substances have been
proved of service independently, but also because certain strains of
trypanosomes resistant to arsenic are known, and trypanosomes can
develop a resistance to arsenic. Such forms, that would not be affected
by the atoxyl, are left open to attack by the antimony salt. Daniels
also recommends combined arsenic and antimony treatment, and (1915)
uses atoxyl and antiluetin.
Atoxyl is best given intramuscularly in 10 per cent. solution in
sterile normal saline solution. Galyl is also said to have given good
results.