capitis_; B, the body louse, gray-back, or cootie (_Pediculus
corporis_); C. the crab or crab louse, _Pediculus pubis_.
]
_Pediculus corporis_ is the only species of louse known to act as
a carrier of disease. Its connection with typhus and trench fever
is admirably described by Brues: “Typhus fever has been well-known
for many years and regarded as a disease characteristic of filthy
surroundings. During our own civil war it claimed many victims among
the inmates of army prisons, and has been endemic though not very
prevalent in many parts of the world in times of peace. Through the
researches of Ricketts and others we now know that typhus is spread
by the body louse and its epidemiology is at once made clear. When
it broke out in Serbia in severe epidemic form, a knowledge of the
method of its transmission made control possible, even under extremely
difficult and unfavorable circumstances.
“Trench fever has attracted notice in the European war zones, to which
it appears to be restricted so far as present knowledge extends.
That it is a new disease is, however, without question an utterly
unwarranted assumption, for it has undoubtedly been brought to Europe
from some little-known quarter of the globe, unless it may have
previously existed in Europe which does not appear probable. During the
latter part of the war it was successively recognized as a distinct
disease, suspected of association with the louse, and soon proved
actually to be louse-borne. We now know that the disease is due to a
living microorganism, probably of such small size that it cannot be
recognized under the microscope. This virus is obtained by the lice
with their meal of blood taken from an infected person. At least five
days must elapse before the louse becomes capable of transmitting the
disease, indicating that the organism must undergo a development of
definite periodicity in the insect. If it is transferred to another
person its bite is not or only rarely infectious, but its excrement
contains the virus and if scratched into the skin, trench fever
develops. Typhus fever is a very dangerous disease with a quite high
death-rate, but trench fever is non-fatal and its importance in the war
zones has been due to its great prevalence and the fact that persons
afflicted with it are often incapacitated for long periods.”
As body lice do not cling to the body except when actually biting, it
is a comparatively easy matter to get rid of them. One has only to
bathe while his clothing is being steamed or soaked in gasoline. The
United States Army set up delousing plants which were nothing but steam
sterilizes on a large scale, and they proved very satisfactory.
The crab louse (_Pediculus pubis_) is short and stout-legged, whitish
on the back, with a distinct reddish cast about the legs. It usually
inhabits the hairy areas about the sex organs, clinging close against
the skin, but is not uncommon in the armpits, and has been found upon
practically every part of the body except the head. The eggs are
attached to the hairs, like those of the head louse; they hatch in less
than a week, and the young crab reproduces at an early age. This little
pest multiplies much more rapidly than either of the other species,
and is besides more easily transmitted from one person to another.
Although the usual means of communication is direct bodily contact,
as in the sexual embrace, it may be transmitted otherwise. The United
States Army memorandum informs us that “this insect is transmitted
mainly by contact in lodging houses, houses of prostitution, bathtubs,
and perhaps occasionally from toilet seats.... Although the crab louse
has not been shown to be a transmitter of disease, still it is very
annoying, and its presence is a reflection on a man’s cleanliness....
The treatment for this condition is to shave the hair of the pubic
region, axillae, chest and legs. This should be followed by an
application of the kerosene and vinegar mixture, followed by a bath
with soap and warm water.” The usual treatment among civilians is the
application of a little mercurial or blue ointment.
OUR FRIEND THE COCKROACH
There are four common species of cockroaches in the United States,
only one of which is native to this country. The American cockroach
(_Periplaneta americana_) is the large winged species so common in
the Middle and Southwestern states. They devour nearly any sort of
food, and have been known to eat the corks out of bottles, while no
less an authority than Vernon Kellogg says that some sailors in San
Francisco sleep with gloves on to keep roaches from gnawing off their
finger-nails. The German roach (_Ectobia germanica_), known also as
the croton-bug, is common in the eastern part of the United States. It
is the smallest species we have, being seldom more than five-eighths of
an inch in length. For some reason or other these roaches are usually
found about water pipes, and are not common in small communities which
have no water systems. The Oriental cockroach (_Blatta orientalis_) is
common also in England, and came to America with the early colonists,
although it is supposed to have originated in Asia. It is larger and
stouter than the croton-bug, and is dark brown or black in color. The
males have short wings, but the females are wingless or practically so.
The Australian roach (_Periplaneta australasiae_) is very much like the
American variety, except for some yellow spots and bands on the thorax
and shoulders. It is less common than any of the others, being found
chiefly in the South.
The life histories of all four species are essentially identical. The
eggs are not deposited singly, but in clusters enclosed in a horny
capsule, the end of which may often be seen projecting from the abdomen
of the female. The young roaches appear very much like their parents,
but do not reach maturity for several months. The flat bodies of
these insects allow them to crawl into small cracks in woodwork and
furniture, and they usually remain hidden during the day, coming out
at night to seek what they may devour. They are really scavengers,
and under certain conditions may be useful in this capacity, but
their omnivorous habits and the intolerable stench of their bodies and
excreta make them the bane of the careful housewife.
“Cockroaches,” observes the indefatigable Herrick, “are among the
most difficult to control of the household pests. They are difficult
to reach because they are especially adapted with their thin, flat
bodies for hiding away in inaccessible cracks, crevices and crannies.
Moreover, they are wary and shy of all baits and traps. The croton-bug
is the most difficult of all to get rid of. It seems to display more
caution in avoiding traps and baits than most of the others, and as it
increases faster, it becomes much more abundant.” Several traps have
been devised and used with some measure of success, and roaches may
often be killed by feeding them plaster of paris mixed with flour, or
by exposing deep jars of stale beer, a delicacy in which they hasten to
drown themselves. Herrick quotes Washburn to the effect that powdered
borax scattered about the kitchen will clear a house of cockroaches.
The best way to completely rid a house of these pests is to fumigate
with hydrocyanic acid gas, made by pouring dilute sulphuric acid on
potassium cyanide. But this method, as I have pointed out elsewhere in
this booklet, is too dangerous for awkward or absent-minded people to
experiment with.
CHIGGERS, TICKS AND FLEAS
The chigger (_Leptus irritans_) is not a true insect, but the immature
form of a mite, related to the spiders. The eggs are laid upon the
ground in the Spring, and when the young chigger hatches it climbs up
a blade of grass and awaits the coming of some animal to which it can
attach itself. At this time it is a very small red creature, barely
large enough to be seen with the unaided eye. It clings to any moving
object which presents itself--usually some passing insect, but quite
frequently a bird or one of the higher animals. After having fed for a
time upon the blood and juices of its mount, the chigger drops off and
changes into the adult mite, which is not parasitic, but feeds largely
upon plant lice.
Man’s contact with the chigger usually comes while walking through
the grass and weeds to which they cling. They cannot bear direct
sunlight, and are not common upon closely clipped lawns unless these
are very densely shaded. The tiny tormenter passes through the finest
of clothing--silk hosiery and underwear are no protection--and attaches
itself to the skin, sucking blood and setting up a severe irritation by
means of some poisonous secretion. The resultant itching is so intense
that one cannot resist the temptation to scratch the affected parts,
which may become infected and cause blood poisoning, and, according to
Hamilton, erysipelas. Although the chigger is not known to disseminate
any particular disease, it is an intolerable nuisance, and has
spoiled many a vacation in the South.
[Illustration:
Fig. IV. Some Common Cockroaches. A, Oriental cockroach (_Blatta
orientalis_), female. B, same, male. C, American cockroach
(_Periplaneta americana_). D, Australian cockroach (_Periplaneta
australasiae_).
]
Some persons avoid chiggers by wearing high boots, others, sprinkle
sulphur in their stockings, while still others use various patent
preparations both before and after the act. My own experience is
that if, directly after coming in from the field, one changes to
chigger-free clothing and rubs whiskey or gasoline upon the parts
likely to be affected, the number of bites will be greatly decreased.
Dr. Vernon C. Allison treats the inflamed areas with potassium
permanganate, but I have had no satisfaction in the use of this remedy.
The fever tick (_Dermacentor venustus_) is the carrier of the disease
known as Rocky Mountain spotted fever. This disease is now restricted
to the Northwestern states, most of the cases occurring in Idaho and
Montana. The life history of the tick is much like that of the chigger.
Hatched from eggs on the ground, the young seed tick mounts a tall
blade of grass or a weed and fastens upon the first animal which comes
along. Forcing the hooked sucking beak into the flesh of the host, it
sucks blood until it is full grown. Then it falls to the ground and
reproduces, dying soon after this duty is done.
Brues describes the fever tick situation as follows: “The _Dermacentor_
ticks occur abundantly on various small wild mammals in the younger
stages and as adults on domesticated animals, such as cattle, and from
these become transferred to man. It has been experimentally shown
that certain rodents are susceptible to the disease, and a tick thus
infected in the nymphal stage can retain the disease organism until
it becomes adult. It may then reach its human host through the medium
of domesticated animals such as cattle. It appears that this is the
ordinary way in which human cases have their origin, i. e., through the
bite of adult ticks, although the newly hatched _seed ticks_ derived
from eggs laid by infected mother ticks are known to contain the
organism also.
“Although Rocky Mountain fever is of minor importance at the present,
it is feared that it may increase its range at any time, since other
ticks of wider distribution are apparently capable of acting as
carriers. Whether this may happen is by no means certain, however,
and the vigorous measures already undertaken to reduce the abundance
of ticks on domesticated animals will undoubtedly bear fruit in the
gradual reduction of this locally much-dreaded disease.”
There are many other species of ticks in the United States, but their
life histories are all very similar. Several of them are believed to be
carriers for various diseases of cattle, but _Dermacentor venustus_ is
the only one known to distribute disease among human beings. The common
Southern cattle-tick (_Margaropus annulatus_) is the sole carrier of
the cattle disease known as Texas fever, which has caused a tremendous
pecuniary loss in several of the Gulf States. The protozoan parasite
which actually causes the trouble is called _Babesia bigemina_, and
Brues refers to the tick’s “becoming infected during its period of
engorgement when feeding on the blood of a diseased animal and then
transmitting the _Babesia_ through its eggs to the young ticks of the
next generation. These may feed on healthy animals the next season,
conveying to them the parasites that have been handed down from the
mother tick.”
[Illustration:
Fig. V. Chiggers and Ticks. A, young and adult chigger (_Leptus
irritans_) redrawn from Herrick. B, Rocky Mountain spotted fever
tick, (_Dermacentor venustus_), after Brues. Male at left, unengorged
female at right.
]
Only two species of fleas are common in dwelling-houses in the United
States. One is the human flea (_Pulex irritans_) and the other is
_Ctenocephalus canis_, found almost universally upon cats and dogs.
One must not suppose, however, that human fleas bite humans only, and
that _Ctenocephalus_ confines its attention to dogs and cats; the human
flea does not scruple on certain occasions of good omen to attack dogs,
cats, rats and mice, while the various other species of fleas bite man
also whenever the spirit moves them. The adult flea lives entirely
upon the blood of its host, obtained through the admirable piercing
and sucking mouthparts. The human flea, according to Herrick, is so
bloodthirsty that it sucks regularly more blood than it can hold, and
the surplus is seen squirting out of the anus while the creature is
sucking more in at the mouth.
The eggs are dropped almost anywhere, and the tiny white larvae develop
in cracks and crevices, feeding upon the organic matter in wood and
rubbish. The pupa is enclosed in a silken cocoon, and the adult may
appear in less than two weeks after the eggs are laid, although the
period is usually somewhat longer.
Until comparatively recent years the flea was looked upon only as
a nuisance, but it has now been discovered that some species act as
agents in spreading bubonic plague, one of the most terrible scourges
known to human history. It appears that the plague is primarily a
rat-disease, and affects the human animal only incidentally. Outbreaks
of plague among human beings are always preceded by an epidemic
among the rats of the same region. The part placed by fleas in the
matter is stated by Brues as follows: “The relation of the flea to
the transmission of plague is due to the fact that rats are regularly
infested by fleas that may become infected with the bacillus of plague,
if it be present in the blood of the host upon which they are feeding.
These bacilli remain in a viable condition for some time in the gut
of the flea and may be transferred to a human subject bitten by an
infected flea. Thus, when a rat dies of plague, its fleas leave it to
search for a new host; if they attach themselves to a rat, that animal
is liable to infection, or if they feed upon a human being, as they
frequently do, the disease may become transferred to man.... The plague
bacilli (_Bacillus pestis_) appear only in fleas that have bitten
infected persons or rats twelve to twenty-six hours previous to death,
for after this time the bacilli do not occur in the blood. The vitality
and virulence of the bacilli are preserved for nearly a week at least
and sometimes fully a month; and there is actually an increase in their
number during the first few days. Infection from these insects may then
occur through their bites, if they contain extremely virulent bacilli,
but probably occurs more commonly by the insects being crushed _in
situ_ after they have punctured the skin.”
From 300,000 to 400,000 cases of bubonic plague occur in India every
year, and nearly half of them terminate fatally. Comparatively few
cases have been reported from the United States in recent years, but
in various places, San Francisco for example, only the most vigorous
and persistent repressive warfare against rats and fleas have prevented
what might have been very serious outbreaks.
Transcriber’s Note:
- Text that was in italics is enclosed by underscores (_italics_).
- Illustrations were moved to the ends of the paragraphs in which
they originally appeared. Their original page numbers are in the list
of illustrations. The list of illustrations was not present in the
original text.
- Inconsistencies in hyphenation have been standardized.
- Minor punctuation errors have been changed without notice.
- Spelling was retained as in the original except for the following
changes:
Page 2: “Our Friend the Cochroach” to “Our Friend the Cockroach”
Page 3: “Europe. Picture Thomas Aquinus” to “Europe. Picture Thomas
Aquinas”
Page 8: “During the Spanish-American war” to “During the
Spanish-American War”
Page 13: “an epidemic which occured” to “an epidemic which occurred”
Page 13: “contended that purulent opthalmia” to “contended that
purulent ophthalmia”
Page 14: “is practically no opthalmia” to “is practically no ophthalmia”
Page 14: “spread of Egyptian opthalmia” to “spread of Egyptian
ophthalmia”
Page 16: “destroyed by the housekeper’s” to “destroyed by the
housekeeper’s”
Page 20: “walls and fences. in” to “walls and fences. In”
Page 20: “and verandas, and is” to “and verandas, and it is”
Page 21: “Lucian Iches of Sante” to “Lucian Iches of Santa”
Page 22: “the province of Sante” to “the province of Santa”
Page 23: “inclines to be irridescent” to “inclines to be iridescent”
Page 25: “this habit of breding” to “this habit of breeding”
Page 27: “a single one developes” to “a single one develops”
Page 32: “The parasites reproduce sexually” to “The parasites
reproduce asexually”
According to other passages in the text, the parasite that causes
malaria reproduces asexually in the human body and sexually in
mosquitoes. This typo was corrected to make the text internally
consistent.
Page 35: “a field near Quemados” to “a field near Quemado”
Page 37: “is that the Aedes” to “is that the _Aedes_”
Page 42: “or Persian insect power” to “or Persian insect powder”
Page 47: “writings of Aristotle, Heroditus” to “writings of
Aristotle, Herodotus”
Page 47: “ease, its antennae oscilate” to “ease, its antennae
oscillate”
Page 48: “antennae, while we followed” to “antennae, while we follow”
Page 49: “is not known, howeve” to “is not known, however”
Page 54: “application of the kerosense” to “application of the
kerosene”
Page 60: “cattle, but _Dermacentor venusta_” to “cattle, but
_Dermacentor venustus_”
Page 63: “years the flea looked” to “years the flea was looked”