natives of the tropics and the south of Europe, which have been justly
called mason-spiders by M. Latreille. One of these (_Mygale nidulans_,
Walckn.), found in the West Indies, "digs a hole in the earth obliquely
downwards about three inches in length, and one in diameter. This
cavity she lines with a tough thick web, which, when taken out,
resembles a leathern purse; but, what is most curious, this house has
a door with hinges, like the operculum of some sea-shells, and herself
and family, who tenant this nest, open and shut the door whenever they
pass and repass. This history was told me," says Darwin, "and the nest,
with its door, shown me by the late Dr. Butt, of Bath, who was some
years physician in Jamaica."[FO]
[Illustration: Nest of the Mason-Spider.
A. The nest shut. B. The nest open. C. The spider, _Mygale cæmentaria_.
D. The eyes magnified. E, F. Parts of the foot and claw magnified.]
The nest of a mason-spider, similar to this, has been obligingly put
into our hands by Mr. Riddle, of Blackheath. It came from the West
Indies, and is probably that of Latreille's clay-kneader (_Mygale
cratiens_), and one of the smallest of the genus. We have since
seen a pair of these spiders in possession of Mr. William Mello, of
Blackheath. The nest is composed of very hard argillaceous clay, deeply
tinged with brown oxide of iron. It is in form of a tube, about one
inch in diameter, between six and seven inches long, and slightly bent
towards the lower extremity--appearing to have been mined into the clay
rather than built. The interior of the tube is lined with a uniform
tapestry of silken web, of an orange-white colour, with a texture
intermediate between India paper and very fine glove leather. But the
most wonderful part of this nest is its entrance, which we look upon
as the perfection of insect architecture. A circular door, about the
size of a crown piece, slightly concave on the outside and convex
within, is formed of more than a dozen layers of the same web which
lines the interior, closely laid upon one another, and shaped so that
the inner layers are the broadest, the outer being gradually less in
diameter, except towards the hinge, which is about an inch long; and in
consequence of all the layers being united there, and prolonged into
the tube, it becomes the thickest and strongest part of the structure.
The elasticity of the materials, also, gives to this hinge the
remarkable peculiarity of acting like a spring, and shutting the door
of the nest spontaneously. It is, besides, made to fit so accurately to
the aperture, which is composed of similar concentric layers of web,
that it is almost impossible to distinguish the joining by the most
careful inspection. To gratify curiosity, the door has been opened and
shut hundreds of times, without in the least destroying the power of
the spring. When the door is shut, it resembles some of the lichens
(_Lecidea_), or the leathery fungi, such as _Polyporus versicolor_
(Micheli), or, nearer still, the upper valve of a young oyster shell.
The door of the nest, the only part seen above ground, being of a
blackish-brown colour, it must be very difficult to discover. (J. R.)
Another mason-spider (_Mygale cæmentaria_, Latr.), found in the south
of France, usually selects for her nest a place bare of grass, sloping
in such a manner as to carry off the water, and of a firm soil, without
rocks or small stones. She digs a gallery a foot or two in depth, and
of a diameter (equal throughout) sufficient to admit of her easily
passing. She lines this with a tapestry of silk glued to the walls.
The door, which is circular, is constructed of many layers of earth
kneaded, and bound together with silk. Externally, it is flat and
rough, corresponding to the earth around the entrance, for the purpose,
no doubt, of concealment: on the inside it is convex, and tapestried
thickly with a web of fine silk. The threads of this door-tapestry are
prolonged, and strongly attached to the upper side of the entrance,
forming an excellent hinge, which, when pushed open by the spider,
shuts again by its own weight, without the aid of spring hinges. When
the spider is at home, and her door forcibly opened by an intruder, she
pulls it strongly inwards, and even when half-opened often snatches it
out of the hand; but when she is foiled in this, she retreats to the
bottom of her den, as her last resource.[FP]
Rossi ascertained that the female of an allied species (_Mygale
sauvagesii_, Latr.), found in Corsica, lived in one of these nests,
with a numerous posterity. He destroyed one of these doors to observe
whether a new one would be made, which it was; but it was fixed
immovably, without a hinge; the spider, no doubt, fortifying herself in
this manner till she thought she might reopen it without danger.[FQ]
[The accompanying illustration shows one of these nests, which is
in my own collection. It was brought from Jamaica, together with the
spider that made it.
[Illustration]
The nest is nearly six inches in length, and is made of a double layer
of silken web. The inner layer is yellowish, with a tinge of red,
and although fine, very tough and strong. The outer layer is thick,
coarse, dark brown, and rather flaky, the dark colour being probably
caused by the earth which is mixed with it. The lid is made of eight
or ten layers of coarse web, overlapping each other like the tiles of
a house-roof, and the entrance of the nest is formed after the same
fashion. If the lid be opened, the inside of the nest is seen to be
of a different make from the exterior, being greyish-white, smooth,
close-textured, and looking much like the finest kid leather.
[Illustration]
The smaller illustration shows the spider in the act of emerging from
its home.]
* * * * *
"The Rev. Revett Shepherd has often noticed, in the fen ditches of
Norfolk, a very large spider (the species not yet determined) which
actually forms a _raft_ for the purpose of obtaining its prey with
more facility. Keeping its station upon a ball of weeds about three
inches in diameter, probably held together by slight silken cords, it
is wafted along the surface of the water upon this floating island,
which it quits the moment it sees a drowning insect. The booty thus
seized it devours at leisure upon its raft, under which it retires when
alarmed by any danger."[FR] In the spring of 1830, we found a spider on
some reeds in the Croydon Canal, which agreed in appearance with Mr.
Shepherd's.
Among our native spiders there are several besides this one, which, not
contented with a web like the rest of their congeners, take advantage
of other materials to construct cells where, "hushed in grim repose,"
they "expect their insect prey." The most simple of those spider-cells
is constructed by a longish-bodied spider (_Aranea holosericea_,
Linn.), which is a little larger than the common hunting-spider. It
rolls up a leaf of the lilac or poplar, precisely in the same manner as
is done by the leaf-rolling caterpillars, upon whose cells it sometimes
seizes to save itself trouble, having first expelled, or perhaps
devoured, the rightful owner. The spider, however, is not satisfied
with the tapestry of the caterpillar, but always weaves a fresh set of
her own, much more close and substantial.
Another spider, common in woods and copses (_Epeira quadrata?_), weaves
together a great number of leaves to form a dwelling for herself, and
in front of it she spreads her toils for entrapping the unwary insects
which stray thither. These, as soon as caught, are dragged into her
den, and stored up for a time of scarcity. Here also her eggs are
deposited and hatched in safety. When the cold weather approaches, and
the leaves of her edifice wither, she abandons it for the more secure
shelter of a hollow tree, where she soon dies; but the continuation of
the species depends upon eggs, deposited in the nest before winter, and
remaining to be hatched with the warmth of the ensuing summer.
The spider's den of united leaves, however, which has just been
described, is not always useless when withered and deserted, for the
dormouse usually selects it as a ready-made roof for its nest of dried
grass. That those old spiders' dens are not accidentally chosen by the
mouse, appears from the fact, that out of about a dozen mouse-nests of
this sort found during winter in a copse between Lewisham and Bromley,
Kent, every second or third one was furnished with such a roof. (J. R.)
Diving Water-Spider.
Though spiders require atmospheric air for respiration, yet one species
well known to naturalists is aquatic in its habits, and lives not
only upon the surface but below the surface of the water, contriving
to carry down with it a sufficiency of air for the support of life
during a considerable period of time. Its subaqueous nest is in fact
a sort of diving-bell, and constitutes a secure and most ingenious
habitation. This spider does not like stagnant water, but prefers low
running streams, canals, and ditches, where she may often be seen in
the vicinity of London and elsewhere, living in her diving-bell, which
shines through the water like a little globe of silver: her singular
economy was first, we believe, described by Clerck,[FS] L. M. de
Lignac,[FT] and De Geer.
"The shining appearance," says Clerck, "proceeds either from an
inflated globule surrounding the abdomen, or from the space between
the body and the water. The spider, when wishing to inhale the air,
rises to the surface, with its body still submersed, and only the part
containing the spinneret rising just to the surface, when it briskly
opens and moves its four teats. A thick coat of hair keeps the water
from approaching or wetting the abdomen. It comes up for air about four
times an hour or oftener, though I have good reason to suppose it can
continue without it for several days together.
"I found in the middle of May one male and ten females, which I put
into a glass filled with water, where they lived together very quietly
for eight days. I put some duckweed (_Lemna_) into the glass to afford
them shelter, and the females began to stretch diagonal threads in
a confused manner from it to the sides of the glass about half-way
down. Each of the females afterwards fixed a close bag to the edge
of the glass, from which the water was expelled by the air from the
spinneret, and thus a cell was formed capable of containing the whole
animal. Here they remained quietly, with their abdomens in their cells,
and their bodies still plunged in the water; and in a short time
brimstone-coloured bags of eggs appeared in each cell, filling it about
a fourth part. On the 7th of July several young ones swam out from one
of the bags. All this time the old ones had nothing to eat, and yet
they never attacked one another as other spiders would have been apt to
do."[FU]
"These spiders," says De Geer, "spin in the water a cell of strong,
closely-woven white silk, in the form of half the shell of a pigeon's
egg, or like a diving-bell. This is sometimes left partly above water,
but at others is entirely submersed, and is always attached to the
objects near it by a great number of irregular threads. It is closed
all round, but has a large opening below, which, however, I found
closed on the 15th of December, and the spider living quietly within,
with her head downwards. I made a rent in this cell, and expelled the
air, upon which the spider came out; yet, though she appeared to have
been laid up for three months in her winter quarters, she greedily
seized upon an insect and sucked it. I also found that the male as well
as the female constructs a similar subaqueous cell, and during summer
no less than in winter."[FV] We have recently kept one of these spiders
for several months in a glass of water, where it built a cell half
under water, in which it laid its eggs.
Cleanliness of Spiders.
When we look at the viscid material with which spiders construct
their lines and webs, and at the rough, hairy covering (with a few
exceptions) of their bodies, we might conclude that they would be
always stuck over with fragments of the minute fibres which they
produce. This, indeed, must often happen, did they not take careful
precautions to avoid it; for we have observed that they seldom, if
ever, leave a thread to float at random, except when they wish to form
a bridge. When a spider drops along a line, for instance, in order to
ascertain the strength of her web, or the nature of the place below
her, she invariably, when she reascends, coils it up into a little
ball, and throws it away. Her claws are admirably adapted for this
purpose, as well as for walking along the lines, as may be readily seen
by a magnifying glass.
[Illustration: Triple-clawed foot of a Spider, magnified.]
There are three claws, one of which acts as a thumb, the others being
toothed like a comb, for gliding along the lines. This structure,
however, unfits it to walk, as flies can do, upon any upright polished
surface like glass; although the contrary[FW] is erroneously asserted
by the Abbé de la Pluche. Before she can do so, she is obliged to
construct a ladder of ropes, as Mr. Blackwell remarks,[FX] by elevating
her spinneret as high as she can, and laying down a step upon which she
stands to form a second, and so on; as any one may try by placing a
spider at the bottom of a very clean wine-glass.
The hairs of the legs, however, are always catching bits of web and
particles of dust; but these are not suffered to remain long. Most
people may have remarked that the house-fly is ever and anon brushing
its feet upon one another to rub off the dust, though we have not seen
it remarked in authors that spiders are equally assiduous in keeping
themselves clean. They have, besides, a very efficient instrument in
their mandibles or jaws, which, like their claws, are furnished with
teeth; and a spider which appears to a careless observer as resting
idly, in nine cases out of ten will be found slowly combing her legs
with her mandibles, beginning as high as possible on the thigh, and
passing down to the claws. The flue which she thus combs off is
regularly tossed away.
With respect to the house-spider (_A. domestica_), we are told in
books, that "she from time to time clears away the dust from her
web, and sweeps the whole by giving it a shake with her paw, so
nicely proportioning the force of her blow, that she never breaks
anything."[FY] That spiders may be seen shaking their webs in this
manner, we readily admit; though it is not, we imagine, to clear them
of dust, but to ascertain whether they are sufficiently sound and
strong.
We recently witnessed a more laborious process of cleaning a web
than merely shaking it. On coming down the Maine by the steamboat
from Frankfort, in August, 1829, we observed the geometric-net of
a conic-spider (_Epeira conica_, Walck.) on the framework of the
deck, and as it was covered with flakes of soot from the smoke of
the engine, we were surprised to see a spider at work on it; for, in
order to be useful, this sort of net must be clean. Upon observing it
a little closely, however, we perceived that she was not constructing
a net, but dressing up an old one; though not, we must think, to save
trouble, so much as an expenditure of material. Some of the lines she
dexterously stripped of the flakes of soot adhering to them; but in
the greater number, finding that she could not get them sufficiently
clean, she broke them quite off, bundled them up, and tossed them over.
We counted five of these packets of rubbish which she thus threw away,
though there must have been many more, as it was some time before we
discovered the manoeuvre, the packets being so small as not to be
readily perceived, except when placed between the eye and the light.
When she had cleared off all the sooty lines, she began to replace them
in the usual way; but the arrival of the boat at Mentz put an end to
our observations. (J. R.) Bloomfield, the poet, having observed the
disappearance of these bits of ravelled web, imagined that the spider
swallowed them; and even says that he observed a garden spider moisten
the pellets before swallowing them![FZ] Dr. Lister, as we have already
seen, thought the spider retracted the threads within the abdomen.
_CHAPTER XIX._
STRUCTURES OF GALL-FLIES AND APHIDES.
Many of the processes which we have detailed bear some resemblance to
our own operations of building with materials cemented together; but
we shall now turn our attention to a class of insect-architects, who
cannot, so far as we know, be matched in prospective skill by any of
the higher orders of animals. We refer to the numerous family which
have received the name of gall-flies,--a family which, as yet, is
very imperfectly understood, their economy being no less difficult to
trace than their species is to arrange in the established systems of
classification; though the latter has been recently much improved by
Mr. Westwood.
[Illustration: Small berry-shaped galls of the oak leaf, produced by
_Cynips quercus folii_?]
One of the most simple and very common instances of the nests
constructed by gall-insects, may be found in abundance during the
summer, on the leaves of the rose-tree, the oak, the poplar, the willow
(_Salix viminalis_), and many other trees, in the globular form of
a berry, about the size of a currant, and usually of a green colour,
tinged with red, like a ripe Alban or Baltimore apple.
When this psuedo-apple in miniature is cut into, it is found to be
fresh, firm, juicy, and hollow in the centre, where there is either
an egg or a grub safely lodged, and protected from all ordinary
accidents. Within this hollow ball the egg is hatched, and the grub
feeds securely on its substance, till it prepares for its winter sleep,
before changing into a gall-fly (_Cynips_) in the ensuing summer. There
is a mystery as to the manner in which this gall-fly contrives to
produce the hollow miniature apples, each enclosing one of her eggs;
and the doubts attendant upon the subject cannot, so far as our present
knowledge extends, be solved, except by plausible conjecture. Our
earlier naturalists were of opinion that it was the grub which produced
the galls, by eating, when newly hatched, through the cuticle of the
leaf, and remaining till the juices flowing from the wound enveloped
it, and acquired consistence by exposure to the air. This opinion,
however, plausible as it appeared to be, was at once disproved by
finding unhatched eggs on opening the galls.
[Illustration: Ovipositor of Gall-fly, greatly magnified.]
There can be no doubt, indeed, that the mother gall-fly makes a hole
in the plant for the purpose of depositing her eggs. She is furnished
with an admirable ovipositor for that express purpose, and Swammerdam
actually saw a gall-fly thus depositing her eggs, and we have recently
witnessed the same in several instances. In some of these insects
the ovipositor is conspicuously long, even when the insect is at
rest; but in others, not above a line or two of it is visible, till
the belly of the insect be gently pressed. When this is done to the
fly that produces the currant-gall of the oak, the ovipositor may be
seen issuing from a sheath in form of a small curved needle, of a
chestnut-brown colour, and of a horny substance, and three times as
long as it at first appeared.
[Illustration: Gall-fly, and mechanism of ovipositor, greatly
magnified.]
What is most remarkable in this ovipositor is, that it is much longer
than the whole body of the insect, in whose belly it is lodged in a
sheath, and, from its horny nature, it cannot be either shortened or
lengthened. It is on this account that it is bent into the same curve
as the body of the insect. The mechanism by which this is effected is
similar to that of the tongue of the woodpeckers (_Picidæ_), which,
though rather short, can be darted out far beyond the beak, by means of
a forked bone at the root of the tongue, which is thin and rolled up
like the spring of a watch. The base of the ovipositor of the gall-fly
is, in a similar way, placed near the anus, runs along the curvature of
the back, makes a turn at the breast, and then, following the curve of
the belly, appears again near where it originates. We copy from Réaumur
his accurate sketch of this remarkable structure.
With this instrument the mother gall-fly pierces the part of a plant
which she selects, and, according to our older naturalists, "ejects
into the cavity a drop of her corroding liquor, and immediately
lays an egg or more there; the circulation of the sap being thus
interrupted, and thrown, by the poison, into a fermentation that burns
the contiguous parts and changes the natural colour. The sap, turned
from its proper channel, extravasates and flows round the eggs, while
its surface is dried by the external air, and hardens into a vaulted
form."[GA] Kirby and Spence tell us, that the parent fly introduces
her egg "into a puncture made by her curious spiral sting, and in a
few hours it becomes surrounded with a fleshy chamber."[GB] M. Virey
says, the gall tubercle is produced by irritation, in the same way as
an inflamed tumor in an animal body, by the swelling of the cellular
tissue and the flow of liquid matter, which changes the organization,
and alters the natural external form.[GC] This seems to be the received
doctrine at present in France.[GD]
Sprengel, speaking of the rose-willow, says, the insect in spring
deposits its eggs in the leaf buds. "The new stimulus attracts the
sap,--the type of the part becomes changed, and from the prevailing
acidity of the animal juice, it happens, that in the rose and
stock-shaped leaves which are pushed out, a red instead of a green
colour is evolved."[GE]
[Illustration: Bedeguar Gall of the Rose, produced by _Cynips rosæ_.]
Without pretending positively to state facts which are, perhaps, beyond
human penetration, we may view the process in a rather different
light. (J. R.) Following the analogy of what is _known_ to occur in
the case of the saw-flies, after the gall-fly has made a puncture
and pushed her egg into the hole, we may suppose that she covers it
over with some adhesive gluten or gum, or the egg itself, as is usual
among moths, &c., may be coated over with such a gluten. In either of
these two cases, the gluten will prevent the sap that flows through
the puncture from being scattered over the leaf and wasted; and the
sap, being thus confined to the space occupied by the eggs, will
expand and force outwards the pellicle of gluten that confines it,
till becoming thickened by evaporation and exposure to the air, it at
length shuts up the puncture, stops the further escape of the sap, and
the process is completed. This explanation will completely account for
the globular form of the galls alluded to; that is, supposing the egg
of the gall-fly to be globular, and covered or coated with a pellicle
of gluten of uniform thickness, and consequently opposing uniform
resistance, or rather uniform expansibility, to the sap pressing from
within. It will also account for the remarkable uniformity in the size
of the gall apples; for the punctures and the eggs being uniform in
size, and the gluten, by supposition, uniform in quantity, no more than
the same quantity of sap can escape in such circumstances.
But though this explanation appears to be plausible, it is confessedly
conjectural; for though Swammerdam detected a gall-fly in the act of
depositing her eggs, he did not attend to this circumstance; and in
the instances which we have observed, some unlucky accident always
prevented us from following up our observations. The indefatigable
Réaumur, on one occasion, thought he would make sure of tracing the
steps of the process in the case of the gall-fly which produces the
substance called _bedeguar_ on the wild rose-tree, and to which we
shall presently advert. His plan was to enclose in a box, in which a
brood of flies had just been produced from a bedeguar, a living branch
from a wild rose-tree; but, to his great disappointment, no eggs were
laid, and no bedeguar formed. Upon further investigation, he discovered
that the brood of flies produced from the bedeguar were not the genuine
bedeguar insects at all, but one of the parasite ichneumons (_Callimone
bedeguaris_, Stephens), which had surreptitiously deposited their eggs
there, in order to supply their young with the bedeguar grubs, all of
which they appeared to have devoured. It may prove interesting to look
into the remarkable structure of the bedeguar itself, which is very
different from the globular galls above described.
[Illustration: One of the bristles of the Bedeguar of the Rose
magnified.]
The gall-fly of the willow (_Cynips viminalis_) deposits, as we have
just seen, only a single egg on one spot; but the bedeguar insect lays
a large cluster of eggs on the extremity of a growing branch of the
wild rose-tree, making, probably, a proportionate number of punctures
to procure materials for the future habitation of her young progeny.
As in the former case, also, each of these eggs becomes (as we may
suppose) surrounded with the sap of the rose, enclosed in a pellicle of
gluten. The gluten, however, of the bedeguar insect is not, it would
appear, sufficiently tenacious to confine the flowing sap within the
dimensions of any of the little clustered globes containing the eggs,
for it oozes out from numerous cracks or pores in the pellicle; which
cracks or pores, however, are not large enough to admit a human hair.
But this, so far from being a defect in the glutinous pellicle of the
bedeguar fly, is, as we shall presently see, of great utility. The sap
which issues from each of these pores, instead of being evaporated and
lost, shoots out into a reddish-coloured, fibrous bristle.
It is about half an inch long, and, from the natural tendency of the
sap of the rose-tree to form prickles, these are all over studded with
weak pricklets. The bedeguar, accordingly, when fully formed, has some
resemblance, at a little distance, to a tuft of reddish-brown hair
or moss stuck upon the branch. Sometimes this tuft is as large as a
small apple, and of a rounded but irregular shape; at other times it
is smaller, and in one instance mentioned by Réaumur, only a single
egg had been laid on a rose-leaf, and, consequently, only one tuft was
produced. Each member of the congeries is furnished with its own tuft
of bristles, arising from the little hollow globe in which the egg or
the grub is lodged.
The prospective wisdom of this curious structure is admirable. The
bedeguar grubs live in their cells through the winter, and as their
domicile is usually on one of the highest branches, it must be exposed
to every severity of the weather. But the close, non-conducting, warm,
mossy collection of bristles, with which it is surrounded, forms for
the soft, tender grubs a snug protection against the winter's cold,
till, through the influence of the warmth of the succeeding summer,
they undergo their final change into the winged state; preparatory
to which they eat their way with their sharp mandibles through the
walls of their little cells, which are now so hard as to be cut with
difficulty by a knife. (J. R.)
Another structure, similar in principle, though different in
appearance, is very common upon oak-trees, the termination of a branch
being selected as best suited for the purpose. This structure is rather
larger than a filbert, and is composed of concentric leaves diverging
from the base, and expanding upwards, somewhat like an artichoke.
Whether this leafy structure is caused by a superinduced disease,
as the French think, or by the form of the pores in the pellicle of
gluten surrounding the eggs, or rather by the tendency of the exuding
sap of the oak to form leaves, has not been ascertained; but that it
is intended, as in the case of the bedeguar, to afford an efficient
protection against the weather to the included eggs or grubs, there can
be no doubt.
[Illustration: Artichoke Gall of the Oak-bud, with Gall-fly (_Cynips
quercus gemmæ_), natural size, and its ovipositor (_a_) magnified.]
From the very nature of the process of forming willow-galls, bedeguar,
and the artichoke of the oak, whatever theory be adopted, it will
be obvious that their growth must be rapid; for the thickening of
the exuded sap, which is quickly effected by evaporation, will soon
obstruct and finally close the orifice of the puncture made by the
parent insect. It is accordingly asserted by Réaumur and other
observers, that all the species of galls soon reach their full growth.
[Illustration: Leafy Gall of Dyer's Broom, produced by _Cynips
genistæ_? A, gall, natural size; B, a leaflet magnified.]
A very minute reddish-coloured grub feeds upon dyer's broom
(_Genista_), producing a sort of gall, frequently globular, but always
studded with bristles, arising from the amorphous leaves. The stem of
the shrub passes through this ball, which is composed of a great number
of leaves, shorter and broader than natural, and each rolled into the
form of a horn, the point of which ends in a bristle. In the interior
we find a thick fleshy substance, serving to sustain the leaves, and
also for the nourishment of the grubs, some of which are within and
some between the leaves. They are in prodigious numbers,--hundreds
being assembled in the small gall, and so minute as scarcely to be
perceived without the aid of a magnifying glass. The bud of the plant
attacked by those grubs, instead of forming a shoot, pushes out
nothing but leaves, and these are all rolled, and turned round the
stem. Some shrubs have several of these galls, which are of various
sizes, from that of a filbert to that of a walnut.
A similar but still more beautiful production is found upon one of the
commonest of our indigenous willows (_Salix purpurea_), which takes
the name of _rose-willow_, more probably from this circumstance than
from the red colour of its twigs. The older botanists, not being aware
of the cause of such excrescences, considered the plants so affected
as distinct species; and old Gerard accordingly figures and describes
the rose-willow as "not only making a gallant show, but also yielding
a most cooling air in the heat of summer, being set up in houses for
decking the same." The production in question, however, is nothing more
than the effect produced by a species of gall-fly (_Cynips salicis_)
depositing its eggs in the terminal shoot of a twig, and, like the
bedeguar and the oak artichoke, causing leaves to spring out, of a
shape totally different from the other leaves of the tree, and arranged
very much like the petals of a rose. Decandolle says it is found
chiefly on the _Salix helix_, _S. alba_, and _S. riparia_.[GF]
A production very like that of the rose-willow may be commonly met with
on the young shoots of the hawthorn, the growth of the shoot affected
being stopped, and a crowded bunch of leaves formed at the termination.
These leaves, besides being smaller than natural, are studded with
short bristly prickles, from the sap (we may suppose) of the hawthorn
being prevented from rising into a fresh shoot, and thrown out of
its usual course in the formation of the arms. These bristles appear
indiscriminately on both sides of the leaves, some of which are bent
inwards, while others diverge in their natural manner.
This is not caused by the egg or grub of a true gall-fly, but by the
small white tapering grub of some dipterous insect, of which we have
not ascertained the species, but which is, probably, a _cecidomyia_.
Each terminal shoot is inhabited by a number of these--not lodged in
cells, however, but burrowing indiscriminately among the half-withered
brown leaves which occupy the centre of the production. (J. R.)
A more remarkable species of gall than any of the above we discovered,
in June, 1829, on the twig of an oak in the grounds of Mr. Perkins,
at Lee, in Kent. When we first saw it, we imagined that the twig was
beset with some species of the lanigerous aphides, similar to what is
vulgarly called the American or white blight (_Aphis lanata_); but
on closer examination we discarded this notion. The twig was indeed
thickly beset with a white downy, or rather woolly, substance around
the stem at the origin of the leaves, which did not appear to be
affected in their growth, being well formed, healthy, and luxuriant. We
could not doubt that the woolly substance was caused by some insect;
but though we cut out a portion of it, we could not detect any egg
or grub, and we therefore threw the branch into a drawer, intending
to keep it as a specimen, whose history we might complete at some
subsequent period.
[Illustration: Semi-Gall of the Hawthorn, produced by _Cecidomyia_?
drawn from a specimen.]
A few weeks afterwards, on opening this drawer, we were surprised to
see a brood of several dozens of a species of gall-fly (_Cynips_),
similar in form and size to that whose eggs cause the bedeguar of the
rose, and differing only in being of a lighter colour, tending to
a yellowish brown. We have since met with a figure and description
of this gall in Swammerdam. We may remark that the above is not the
first instance which has occurred in our researches, of gall insects
outliving the withering of the branch or leaf from which they obtain
their nourishment.
[Illustration: Woolly Gall of the Oak, less than the natural size,
caused by a _Cynips_, and drawn from a specimen.]
The woolly substance on the branch of the oak which we have described
was similarly constituted with the bedeguar of the rose, with this
difference, that instead of the individual cells being diffused
irregularly through the mass, they were all arranged at the off-goings
of the leaf-stalks, each cell being surrounded with a covering of the
vegetable wool, which the stimulus of the parent egg, or its gluten,
had caused to grow, and from each cell a perfect fly had issued. We
also remarked that there were several small groups of individual cells,
each of which groups was contained in a species of calyx or cup of
leaf-scales, as occurs also in the well-known gall called the oak-apple.
We were anxious to watch the proceedings of these flies in the
deposition of their eggs, and the subsequent developments of the
gall-growths; and endeavoured for that purpose to procure a small oak
plant in a garden-pot; but we did not succeed in this: and though they
alighted on rose and sweet-briar trees, which we placed in their way,
we never observed that they deposited any eggs upon them. In a week or
two the whole brood died, or disappeared. (J. R.)
There are some galls, formed on low-growing plants, which are covered
with down, hair, or wool, though by no means so copiously as the one
which we have just described. Among the plants so affected are the
germander speedwell, wild thyme, ground-ivy, and others to which we
shall afterwards advert.
[Illustration: Oak-apple Galls, one being cut open to show the vessels
running to granules.]
The well-known oak-apple is a very pretty example of the galls formed
by insects; and this, when compared with other galls which form on the
oak, shows the remarkable difference produced on the same plant by the
punctures of insects of different species. The oak-apple is commonly
as large as a walnut or small apple, rounded, but not quite spherical,
the surface being irregularly depressed in various places. The skin is
smooth, and tinged with red and yellow, like a ripe apple; and at the
base there is, in the earlier part of the summer, a calyx or cup of
five or six small brown scaly leaves; but these fall off as the season
advances. If an oak-apple be cut transversely, there is brought into
view a number of oval granules, each containing a grub, and embedded
in a fruit-looking fleshy substance, having fibres running through
it. As these fibres, however, run in the direction of the stem, they
are best exhibited by a vertical section of the gall; and this also
shows the remarkable peculiarity of each fibre terminating in one of
the granules, like a footstalk, or rather like a vessel for carrying
nourishment. Réaumur, indeed, is of opinion that these fibres are the
diverted nervures of the leaves, which would have sprung from the bud
in which the gall-fly had inserted her eggs, and actually do carry
sap-vessels throughout the substance of the gall.
[Illustration: Root Galls of the Oak, produced by _Cynips quercus
inferus_? drawn from a specimen.]
Réaumur says the perfect insects (_Cynips quercus_) issued from his
galls in June and the beginning of July, and were of a reddish-amber
colour. We have procured insects, agreeing with Réaumur's description,
from galls formed on the bark or wood of the oak, at the line of
junction between the root and the stem. These galls are precisely
similar in structure to the oak-apple, and are probably formed at a
season when the fly perceives, instinctively, that the buds of the
young branches are unfit for the purpose of nidification.
There is another oak-gall, differing little in size and appearance from
the oak-apple, but which is very different in structure, as, instead
of giving protection and nourishment to a number of grubs, it is only
inhabited by one. This sort of gall, besides, is hard and woody on the
outside, resembling a little wooden ball of a yellowish colour, but
internally of a soft, spongy texture. The latter substance, however,
encloses a small hard gall, which is the immediate residence of the
included insect. Galls of this description are often found in clusters
of from two to seven, near the extremity of a branch, not incorporated,
however, but distinctly separate.
[Illustration: Woody Gall on a Willow branch, drawn from a specimen.]
We have obtained a fly very similar to this from a very common gall,
which is formed on the branches of the willow. Like the one-celled
galls just described, this is of a hard, ligneous structure, and forms
an irregular protuberance, sometimes at the extremity, and sometimes
on the body, of a branch. But instead of one, this has a considerable
number of cells, irregularly distributed through its substance. The
structure is somewhat spongy, but fibrous; and externally the bark is
smoother than that of the branch upon which it grows. (J. R.)
The currant-galls (as the French call them) of the oak are exactly
similar, when formed on the leaves, to those which we have first
described as produced on the leaves of the willow and other trees. But
the name of currant-gall seems still more appropriate to an excrescence
which grows on the catkins of the oak, giving them very much the
appearance of a straggling branch of currants or bird-cherries. The
galls resemble currants which have fallen from the tree before being
ripe. These galls do not seem to differ from those formed on the
leaves of the oak; and are probably the production of the same insect,
which selects the catkin in preference, by the same instinct that the
oak-apple gall-fly, as we have seen, sometimes deposits its eggs in the
bark of the oak near the root.
[Illustration: Currant Gall of the catkins of the Oak, produced by
_Cynips quercus pedunculi_?]
The gall of the oak, which forms an important dye-stuff, and is used
in making writing-ink, is also produced by a _Cynips_, and has been
described in the 'Library of Entertaining Knowledge' (Vegetable
Substances, p. 16). The employment of the _Cynips psenes_ for ripening
figs is described in the same volume, p. 244.
[Illustration: Gall of the Hawthorn Weevil, drawn from specimen. _a_,
Opened to show the grub.]
Gall of a Hawthorn Weevil.
In May, 1829, we found on a hawthorn at Lee, in Kent, the leaves at
the extremity of a branch neatly folded up in a bundle, but not quite
so closely as is usual in the case of leaf-rolling caterpillars. On
opening them, there was no caterpillar to be seen, the centre being
occupied with a roundish, brown-coloured, woody substance, similar to
some excrescences made by gall-insects (_Cynips_). Had we been aware
of its real nature, we should have put it immediately under a glass or
in a box, till the contained insect had developed itself; but instead
of this, we opened the ball, where we found a small yellowish grub
coiled up, and feeding on the exuding juices of the tree. As we could
not replace the grub in its cell, part of the walls of which we had
unfortunately broken, we put it in a small pasteboard box with a fresh
shoot of hawthorn, expecting that it might construct a fresh cell.
This, however, it was probably incompetent to perform: it did not at
least make the attempt, and neither did it seem to feed on the fresh
branch, keeping in preference to the ruins of its former cell. To our
great surprise, although it was thus exposed to the air, and deprived
of a considerable portion of its nourishment, both from the part of
the cell having been broken off, and from the juices of the branch
having been dried up, the insect went through its regular changes, and
appeared in the form of a small greyish-brown beetle of the weevil
family. The most remarkable circumstance in the case in question, was
the apparent inability of the grub to construct a fresh cell after
the first was injured,--proving, we think, beyond a doubt, that it is
the puncture made by the parent insect when the egg is deposited that
causes the exudation and subsequent concretion of the juices forming
the gall. These galls were very abundant during the summer of 1830. (J.
R.)
A few other instances of beetles producing galls are recorded by
naturalists. Kirby and Spence have ascertained, for example, that the
bumps formed on the roots of kedlock or charlock (_Sinapis arvensis_)
are inhabited by the larvæ of a weevil (_Curculio contractus_, Marsham;
and _Rhynchoenus assimilis_, Fabr.); and it may be reasonably supposed
that either the same or similar insects cause the clubbing of the
roots of cabbages, and the knob-like galls on turnips, called in some
places the _anbury_. We have found them also infesting the roots of
the hollyhock (_Alcea rosea_). They are evidently beetles of an allied
genus which form the woody galls sometimes met with on the leaves of
the guelder-rose (_Viburnum_), the lime-tree (_Tilia Europæa_), and the
beech (_Fagus sylvatica_).
There are also some two-winged flies which produce woody galls on
various plants, such as the thistle-fly (_Tephritis cardui_, Latr.).
The grubs of this pretty fly produce on the leaf-stalks of thistles
an oblong woody knob. On the common white briony (_Bryonia dioica_)
of our hedges may be found a very pretty fly of this genus, of a
yellowish-brown colour, with pellucid wings, waved much like those of
the thistle-fly with yellowish brown. This fly lays its eggs near a
joint of the stem, and the grubs live upon its substance. The joint
swells out into an oval form, furrowed in several places, and the
fly is subsequently disclosed. In its perfect state, it feeds on
the blossom of the briony. (J. R.) Flies of another minute family,
the gall-gnats (_Cecidomyiæ_, Latr.), pass the first stage of their
existence in the small globular cottony galls which abound on germander
speedwell (_Veronica chamædrys_), wild thyme (_Thymus serpyllum_), and
ground-ivy (_Glechoma hederacea_). The latter is by no means uncommon,
and may be readily recognised.
Certain species of plant-lice (_Aphides_), whose complete history would
require a volume, produce excrescences upon plants which may with some
propriety be termed galls, or semi-galls. Some of these are without
any aperture, whilst others are in form of an inflated vesicle, with
a narrow opening on the under side of a leaf, and expanding (for the
most part irregularly) into a rounded knob on its upper surface. The
mountain-ash (_Pyrus aucuparia_) has its leaves and young shoots
frequently affected in this way, and sometimes exhibits galls larger
than a walnut or even than a man's fist; at other times they do not
grow larger than a filbert. Upon opening one of these, they are found
to be filled with the _aphides sorbi_. If taken at an early stage of
their growth, they are found open on the under side of the leaf, and
inhabited only by a single female aphis, pregnant with a numerous
family of young. In a short time the aperture becomes closed, in
consequence of the insect making repeated punctures round its edge,
from which sap is exuded and forms an additional portion of the walls
of the cell.
[Illustration: A Plant-Louse (_Aphis_), magnified.]
In this early stage of its growth, however, the gall does not, like
the galls of the cynips, increase very much in dimensions. It is after
the increase of the inhabitants by the young brood that it grows with
considerable rapidity; for each additional insect, in order to procure
food, has to puncture the wall of the chamber and suck the juices, and
from the punctures thus made the sap exudes, and enlarges the walls.
As those galls are closed all round in the more advanced state, it
does not appear how the insects can ever effect an exit from their
imprisonment.
[Illustration: Galls produced on the leaves and leaf-stalks of the
Poplar by _Eriosoma populi_, with the various forms of the insects,
winged, not winged, and covered with wool, both of the natural size and
magnified.]
A much more common production, allied to the one just described, may
be found on the poplar in June and July. Most of our readers may have
observed, about midsummer, a small snow-white tuft of downy-looking
substance floating about on the wind, as if animated. Those tufts
of snow-white down are never seen in numbers at the same time, but
generally single, though some dozens of them may be observed in the
course of one day. This singular object is a four-winged fly (_Eriosoma
populi_, Leach), whose body is thickly covered with long down--a
covering which seems to impede its flight, and make it appear more
like an inanimate substance floating about on the wind, than impelled
by the volition of a living animal. This pretty fly feeds upon the
fresh juices of the black poplar, preferring that of the leaves and
leaf-stalks, which it punctures for this purpose with its beak. It
fixes itself with this design to a suitable place upon the principal
nervure of the leaf, or upon the leaf-stalk, and remains in the same
spot till the sap, exuding through the punctures, and thickening by
contact with the air, surrounds it with a thick fleshy wall of living
vegetable substance, intermediate in texture between the wood and the
leaf, being softer than the former and harder than the latter. In this
snug little chamber, secure from the intrusion of lady-birds and the
grubs of aphidivorous flies (_Syrphi_), she brings forth her numerous
brood of young ones, who immediately assist in enlarging the extent
of their dwelling, by puncturing the walls. In one respect, however,
the galls thus formed differ from those of the mountain-ash just
described,--those of the poplar having always an opening left into some
part of the cell, and usually in that portion of it which is elongated
into an obtuse beak. From this opening the young, when arrived at
the winged state, make their exit, to form new colonies; and, during
their migrations, attract the attention of the most incurious by the
singularity of their appearance. (J. R.)
On the black poplar there may be found, later in the season than the
preceding, a gall of a very different form, though, like the other, it
is for the most part on the leaf-stalk. The latter sort of galls are
of a spiral form; and though they are closed, they open upon slight
pressure, and appear to be formed of two laminæ, twisted so as to
unite. It is at this opening that an aperture is formed spontaneously
for the exit of the insects, when arrived at a perfect state. In galls
of this kind we find aphides, but of a different species from the
lanigerous ones, which form the horn-shaped galls above described.
Leaf-Rolling Aphides.
It may not be improper to introduce here a brief sketch of some other
effects, of a somewhat similar kind, produced on leaves by other
species of the same family (_Aphidæ_). In all the instances of this
kind which we have examined, the form which the leaf takes serves as a
protection to the insects, both from the weather and from depredators.
That there is design in it appears from the circumstance of the aphides
crowding into the embowering vault which they have formed; and we are
not quite certain whether they do not puncture certain parts of the
leaf for the very purpose of making it arch over them; at least, in
many cases, such as that of the hop-fly (_Aphis humuli_), though the
insects are in countless numbers, no arching of the leaves follows.
The rose-plant louse, again (_Aphis rosæ_), sometimes arches the
leaves, but more frequently gets under the protecting folds of the
half-expanded leaf-buds. (J. R.)
[Illustration: Leaf of the Currant-bush, bulged out by the _Aphis
ribis_.]
One of the most common instances of what we mean occurs on the leaves
of the currant-bush, which may often be observed raised up into
irregular bulgings, of a reddish-brown colour. On examining the under
side of such a leaf there will be seen a crowd of small insects, some
with and some without wings, which are the _Aphides ribis_ in their
different stages, feeding securely and socially on the juices of the
leaf.
The most remarkable instance of this, however, which we have seen,
occurs on the leaves of the elm, and is caused by the _Aphis ulmi_.
The edge of an elm-leaf inhabited by those aphides is rolled up in an
elegant convoluted form, very much like a spiral shell; and in the
embowered chamber thus formed the insects are secure from rain, wind,
and partially from the depredations of carnivorous insects. One of
their greatest enemies, the lady-bird (_Coccinella_), seldom ventures,
as we have remarked, into concealed corners except in cold weather,
and contrives to find food enough among the aphides which feed openly
and unprotected, such as the zebra aphides of the alder (_Aphides
sambuci_). The grubs, however, of the lady-bird, and also those of the
aphidivorous flies (_Syrphi_), may be found prying into the most secret
recesses of a leaf to prey upon the inhabitants, whose slow movements
disqualify them from effecting an escape. (J. R.)
The effect of the puncture of aphides on growing plants is strikingly
illustrated in the shoots of the lime-tree and several other plants,
which become bent and contorted on the side attacked by the insects, in
the same way that a shoot might warp by the loss of its juices on the
side exposed to a brisk fire. The curvings thus effected become very
advantageous to the insects, for the leaves sprouting from the twig,
which naturally grow at a distance from each other, are brought close
together in a bunch, forming a kind of nosegay, that conceals all the
colour of the sprig, as well as the insects which are embowered under
it, protecting them against the rain and the sun, and at the same time
hiding them from observation. It is only requisite, however, where
they have formed bowers of this description, to raise the leaves, in
order to see the little colony of the aphides,--or the remains of those
habitations which they have abandoned. We have sometimes observed
sprigs of the lime-tree, of a thumb's thickness, portions of which
resembled spiral screws; but we could not certainly have assigned the
true cause for this twisting, had we not been acquainted with the
manner in which aphides contort the young shoots of this tree.[GG] The
shoots of the gooseberry and the willow are sometimes contorted in the
same way, but not so strikingly as the shoots of the lime.
[Illustration: Shoot of the Lime-tree contorted by the punctures of the
_Aphis tiliæ_.]
Pseudo-Galls.
It may not be out of place to mention here certain anomalous
excrescences upon trees and other plants, which, though they much
resemble galls, are not so distinctly traceable to the operations of
any insect. In our researches after galls, we have not unfrequently
met with excrescences which so very much resemble them, that before
dissection we should not hesitate to consider them as such, and
predict that they formed the nidus of some species of insects. In more
instances than one we have felt so strongly assured of this, that we
have kept several specimens for some months, in nurse-boxes, expecting
that in due time the perfect insect would be disclosed.
One of these pseudo-galls occurs on the common bramble (_Rubus
fruticosus_), and bears some resemblance to the bedeguar of the rose
when old and changed by weather. It clusters round the branches in the
form of irregular granules, about the size of a pea, very much crowded,
the whole excrescence being rather larger than a walnut. We expected
to find this excrescence full of grubs, and were much surprised to
discover, upon dissection, that it was only a diseased growth of the
plant, caused (it might be) by the puncture of an insect, but not for
the purpose of a nidus or habitation. (J. R.)
[Illustration: Pseudo-gall of the Bramble, drawn from a specimen.]
Another sort of excrescence is not uncommon on the terminal shoots
of the hawthorn. This is in general irregularly oblong, and the bark
which covers it is of an iron colour, similar to the scoriæ of a
blacksmith's forge. When dissected, we find no traces of insects, but
a hard, ligneous, and rather porous texture. It is not improbable that
this excrescence may originate in the natural growth of a shoot being
checked by the punctures of aphides, or of those grubs which we have
described.
Many of these excrescences, however, are probably altogether
unconnected with insects, and are simply hypertrophic diseases,
produced by too much nourishment, like the wens produced on animals.
Instances of this may be seen at the roots of the hollyhock (_Althea
rosea_) of three or four years' standing; on the stems of the elm and
other trees, immediately above the root; and on the upper branches of
the birch, where a crowded cluster of twigs sometimes grows, bearing
no distant resemblance to a rook's nest in miniature, and provincially
called witch-knots.
[Illustration: Pseudo-galls of the Hawthorn, drawn from specimens.]
One of the prettiest of these pseudo-galls with which we are
acquainted, is produced on the Scotch fir (_Pinus sylvestris_),
by the _Aphis pini_, which is one of the largest species of our
indigenous aphides. The production we allude to may be found, during
the summer months, on the terminal shoots of this tree, in the form
of a small cone, much like the fruit of the tree in miniature, but
with this difference, that the fruit terminates in a point, whereas
the pseudo-gall is nearly globular. Its colour also, instead of being
green, is reddish; but it exhibits the tiled scales of the fruit cone.
We have mentioned this the more willingly that it seems to confirm the
theory which we have hazarded respecting the formation of the bedeguar
of the rose and other true galls--by which we ascribed to the sap,
diverted from its natural course by insects, a tendency to form leaves,
&c., like those of the plant from which it is made to exude.
[Illustration: Pseudo-gall produced by _Aphis_ _pini_ on the Scotch
fir, drawn from a specimen.]
_CHAPTER XX._
ANIMAL GALLS,[GH] PRODUCED BY BREEZE-FLIES AND SNAIL-BEETLES.
The structures which we have hitherto noticed have all been formed of
inanimate materials, or at the most of growing vegetables; but those
to which we shall now advert are actually composed of the flesh of
living animals, and seem to be somewhat akin to the galls already
described as formed upon the shoots and leaves of plants. These were
first investigated by the accurate Vallisnieri, and subsequently by
Réaumur, De Geer, and Linnæus; but the best account which has hitherto
been given of them is by our countryman Mr. Bracey Clark, who differs
essentially from his predecessors as to the mode in which the eggs are
deposited. As, in consequence of the extreme difficulty, if not the
impossibility, of personal observation, it is no easy matter to decide
between the conflicting opinions, we shall give such of the statements
as appear most plausible.
The mother breeze-fly (_Oestrus bovis_, Clark;--_Hypoderma bovis_,
Latr.), which produces the tumours in cattle called _wurbles_ or
_wormuls_ (_quasi_, _worm-holes_), is a two-winged insect, smaller,
but similar in appearance and colour to the carder-bee (p. 75), with
two black bands, one crossing the shoulders and the other the abdomen,
the rest being covered with yellow hair. This fly appears to have
been first discovered by Vallisnieri, who has given a curious and
interesting history of his observations upon its economy. "After having
read this account," says Réaumur, "with sincere pleasure, I became
exceedingly desirous of seeing with my own eyes what the Italian
naturalist had reported in so erudite and pleasing a manner. I did
not then imagine that it would ever be my lot to speak upon a subject
which had been treated with so much care and elegance; but since I have
enjoyed more favourable opportunities than M. Vallisnieri, it was not
difficult for me to investigate some of the circumstances better, and
to consider them under a different point of view. It is not, indeed,
very wonderful to discover something new in an object, though it has
been already carefully inspected with very good eyes, when we sit
down to examine it more narrowly, and in a more favourable position;
while it sometimes happens, also, that most indifferent observers
have detected what had been previously unnoticed by the most skilful
interpreters of nature."[GI]
From the observations made by Réaumur, he concluded that the
mother-fly, above described, deposits her eggs in the flesh of the
larger animals, for which purpose she is furnished with an ovipositor
of singular mechanism. We have seen that the ovipositors in the
gall-flies (_Cynips_) are rolled up within the body of the insect
somewhat like the spring of a watch, so that they can be thrust out to
more than double their apparent length. To effect the same purpose,
the ovipositor of the ox-fly lengthens, by a series of sliding tubes,
precisely like an opera-glass. There are four of these tubes, as may be
seen by pressing the belly of the fly till they come into view. Like
other ovipositors of this sort, they are composed of a horny substance;
but the terminal piece is very different indeed from the same part in
the gall-flies, the tree-hoppers (_Cicadæ_), and the ichneumons, being
composed of five points, three of which are longer than the other
two, and at first sight not unlike a _fleur-de-lis_, though, upon
narrower inspection, they may be discovered to terminate in curved
points, somewhat like the claw of a cat. The two shorter pieces are
also pointed, but not curved; and by the union of the five, a tube is
composed for the passage of the eggs.
It would be necessary, Réaumur confesses, to see the fly employ this
instrument to understand in what manner it acts, though he is disposed
to consider it fit for boring through the hides of cattle. "Whenever I
have succeeded," he adds, "in seeing these insects at work, they have
usually shown that they proceeded quite differently from what I had
imagined; but unfortunately I have never been able to see one of them
pierce the hide of a cow under my eyes."[GJ]
[Illustration: Ovipositor of the Breeze-fly, greatly magnified, with a
claw and part of the tube, distinct.]
Mr. Bracey Clark, taking another view of the matter, is decidedly
of opinion that the fly does not pierce the skin of cattle with its
ovipositor at all, but merely glues its eggs to the hairs, while the
grubs, when hatched, eat their way under the skin. If this be the
fact, as is not improbable, the three curved pieces of the ovipositor,
instead of acting, as Réaumur imagined, like a centre-bit, will only
serve to prevent the eggs from falling till they are firmly glued to
the hair, the opening formed by the two shorter points permitting
this to be effected. This account of the matter is rendered more
plausible, from Réaumur's statement that the deposition of the egg
is not attended by much pain, unless, as he adds, some very sensible
nervous fibres have been wounded. According to this view, we must not
estimate the pain produced by the thickness of the instrument; for the
sting of a wasp, or a bee, although very considerably smaller than the
ovipositor of the ox-fly, causes a very pungent pain. It is, in the
latter case, the poison infused by the sting, rather than the wound,
which occasions the pain; and Vallisnieri is of opinion that the ox-fly
emits some acrid matter along with her eggs, but there is no proof of
this beyond conjecture.
It ought to be remarked, however, that cattle have very thick hides,
which are so far from being acutely sensitive of pain, that in
countries where they are put to draw ploughs and waggons, they find
a whip ineffectual to drive them, and have to use a goad, in form of
an iron needle, at the end of a stick. Were the pain inflicted by the
fly very acute, it would find it next to impossible to lay thirty or
forty eggs without being killed by the strokes of the ox's tail; for
though Vallisnieri supposes that the fly is shrewd enough to choose
such places as the tail cannot reach, Réaumur saw a cow repeatedly flap
its tail upon a part full of the gall-bumps; and in another instance he
saw a heifer beat away a party of common flies from a part where there
were seven or eight gall-bumps. He concludes, therefore, with much
plausibility, that these two beasts would have treated the ox-flies in
the same way, if they had given them pain when depositing their eggs.
The extraordinary effects produced upon cattle, on the appearance of
one of these flies, would certainly lead us to conclude that the pain
inflicted is excruciating. Most of our readers may recollect to have
seen, in the summer months, a whole herd of cattle start off across
a field in full gallop, as if they were racing,--their movements
indescribably awkward--their tails being poked out behind them as
straight and stiff as a post, and their necks stretched to their utmost
length. All this consternation has been known, from the earliest times,
to be produced by the fly we are describing. Virgil gives a correct
and lively picture of it in his Georgies,[GK] of which the following is
a translation, a little varied from Trapp:
Round Mount Alburnus, green with shady oaks,
And in the groves of Silarus, there flies
An insect pest (named _Oestrus_ by the Greeks,
By us _Asilus_): fierce with jarring hum
It drives, pursuing, the affrighted herd
From glade to glade; the air, the woods, the banks
Of the dried river echo their loud bellowing.
Had we not other instances to adduce, of similar terror caused among
sheep, deer, and horses, by insects of the same genus, which are
ascertained not to penetrate the skin, we should not have hesitated to
conclude that Vallisnieri and Réaumur are right, and Mr. Bracey Clark
wrong. In the strictly similar instance of Reindeer-fly (_Oestrus
tarandi_, Linn.), we have the high authority of Linnæus for the fact,
that it lays its eggs _upon_ the skin.
"I remarked," he says, "with astonishment how greatly the reindeer
are incommoded in hot weather, insomuch that they cannot stand still
a minute, no not a moment, without changing their posture, starting,
puffing and blowing continually, and all on account of a little fly.
Even though amongst a herd of perhaps five hundred reindeer, there were
not above ten of those flies, every one of the herd trembled and kept
pushing its neighbour about. The fly, meanwhile, was trying every means
to get at them; but it no sooner touched any part of their bodies, than
they made an immediate effort to shake it off. I caught one of these
insects as it was flying along with its tail protruded, which had at
its extremity a small linear orifice perfectly white. The tail itself
consisted of four or five tubular joints, slipping into each other
like a pocket spying-glass, which this fly, like others, has a power of
contracting at pleasure."[GL]
In another work he is still more explicit. "This well-known fly," he
says, "hovers the whole day over the back of the reindeer, with its
tail protruded and a little bent, upon the point of which it holds a
small white egg, scarcely so large as a mustard-seed, and when it has
placed itself in a perpendicular position, it drops its egg, which
rolls down amongst the hair to the skin, where it is hatched by the
natural heat and perspiration of the reindeer, and the grub eats its
way slowly under the skin, causing a bump as large as an acorn."[GM]
The male and female of the reindeer breeze-fly are figured in the
'Library of Entertaining Knowledge, Menageries,' vol. i. p. 405.
There is one circumstance which, though it appears to us to be of
some importance in the question, has been either overlooked or
misrepresented in books. "While the female fly," say Kirby and Spence,
"is performing the operation of oviposition, the animal attempts to
lash her off as it does other flies, with its tail;"[GN] though this
is not only at variance with their own words in the page but one
preceding, where they most accurately describe "the herd with their
tails in the air, or turned upon their backs, or stiffly stretched out
in the direction of the spine,"[GO] but with the two facts mentioned
above from Réaumur, as well as with common observation. If the ox
then do not attempt to lash off the breeze-fly, but runs with its
tail stiffly extended, it affords a strong presumption that the fly
terrifies him by her buzzing (_asper_, _acerba sonans_), rather than
pains him by piercing his hide: her buzz, like the rattle of the
rattlesnake, being instinctively understood, and intended, it may be,
to prevent an over-population, by rendering it difficult to deposit the
eggs.
The horse breeze-fly (_Gasterophilus equi_, Leach), which produces the
maggots well known by the name of _botts_ in horses, is ascertained
beyond a doubt to deposit her eggs upon the hair; and as insects of the
same genus almost invariably proceed upon similar principles, however
much they may vary in minute particulars, it may be inferred with
justice, that the breeze-flies which produce galls do the same. The
description given by Mr. Bracey Clark, of the proceedings of the horse
breeze-fly, is exceedingly interesting.
"When the female has been impregnated, and her eggs sufficiently
matured, she seeks among the horses a subject for her purpose, and
approaching him on the wing, she carries her body nearly upright in the
air, and her tail, which is _lengthened for the purpose_,[GP] curved
inwards and upwards; in this way she approaches the part where she
designs to deposit the egg; and suspending herself for a few seconds
before it, suddenly darts upon it and leaves the egg adhering to the
hair; she hardly appears to settle, but merely touches the hair with
the egg _held out on the projected point of the abdomen_.[GP] The egg
is made to adhere by means of a glutinous liquor secreted with it. She
then leaves the horse at a small distance, and prepares a second egg,
and poising herself before the part, deposits it in the same way. The
liquor dries, and the egg becomes firmly glued to the hair: this is
repeated by these flies till four or five hundred eggs are sometimes
placed on one horse."
Mr. Clark farther tells us, that the fly is careful to select a part
of the skin which the horse can easily reach with his tongue, such as
the inside of the knee, or the side and back part of the shoulder.
It was at first conjectured, that the horse licks off the eggs thus
deposited, and that they are by this means conveyed into its stomach;
but Mr. Clark says, "I do not find this to be the case, or at least
only by accident; for when they have remained on the hair four or five
days, they become ripe, after which time the slightest application of
warmth and moisture is sufficient to bring forth, in an instant, the
latent larva. At this time, if the tongue of the horse touches the egg,
its operculum is thrown open, and a small, active worm is produced,
which readily adheres to the moist surface of the tongue, and is thence
conveyed with the food to the stomach." He adds, that "a horse which
has no ova deposited on him may yet have botts, by performing the
friendly office of licking another horse that has."[GQ] The irritations
produced by common flies (_Anthomyiæ meteoricæ_, Meigen) are alleged as
the incitement to licking.
The circumstance, however, of most importance to our purpose, is the
agitation and terror produced both by this fly and by another horse
breeze-fly (_Gasterophilus hæmorrhoidalis_, Leach), which deposits
its eggs upon the lips of the horse as the sheep breeze-fly (_Oestrus
ovis_) does on that of the sheep. The first of these is described
by Mr. Clark as "very distressing to the animal, from the excessive
titillation it occasions; for he immediately after rubs his mouth
against the ground, his fore-feet, or sometimes against a tree, with
great emotion; till, finding this mode of defence insufficient, he
quits the spot in a rage, and endeavours to avoid it by galloping
away to a distant part of the field, and if the fly still continues
to follow and teaze him, his last resource is in the water, where the
insect is never observed to pursue him. These flies appear sometimes
to hide themselves in the grass, and as the horse stoops to graze
they dart upon the mouth or lips, and are always observed to poise
themselves during a few seconds in the air, while the egg is prepared
_on the extended point of the abdomen_."[GR]
The moment the second fly just mentioned touches the nose of a sheep,
the animal shakes its head and strikes the ground violently with its
fore-feet, and at the same time holding its nose to the earth, it runs
away, looking about on every side to see if the flies pursue. A sheep
will also smell the grass as it goes, lest a fly should be lying in
wait, and if one be detected, it runs off in terror. As it will not,
like a horse or an ox, take refuge in the water, it has recourse to
a rut or dry dusty road, holding its nose close to the ground, thus
rendering it difficult for the fly to get at the nostril.
[Illustration: _a_, The belly of the grub. _b_, Its back. _c_, The tail
of the grub, greatly magnified. _d_, The bump, or gall, having its
external aperture filled with the tail of the grub.]
When the egg of the ox breeze-fly (_Hypoderma bovis_, Latr.) is
hatched, it immediately (if Mr. Bracey Clark be correct) burrows into
the skin; while, according to Réaumur, it is hatched there. At all
events, the grub is found in a bump on the animal's back, resembling
a gall on a tree,--"a place," says Réaumur, "where food is found in
abundance, where it is protected from the weather, where it enjoys
at all times an equal degree of warmth, and where it finally attains
maturity."[GS] When in an advanced stage, the bumps appear much like
the swellings produced upon the forehead by a smart blow. These, with
the grubs, are represented in the foregoing figure, and also at page
434.
Every bump, according to Réaumur, has in its inside a cavity, which is
a lodging proportionate to the size of the insect. The bump and cavity
also increase in proportion to the growth of the grub. It is not until
about the middle of May that these bumps can be seen full grown. Owing
to particular circumstances, they do not all attain an equal size. The
largest of them are sixteen or seventeen lines in diameter at their
base, and about an inch high; but they are scarcely perceptible before
the beginning or during the course of the winter.
[Illustration: Fly, maggot, and grub of the Ox breeze-fly, with a
microscopic view of the maggot.]
It is commonly upon young cattle, such, namely, as are two or three
years old, that the greatest number of bumps is found; it being rare
to observe them upon very old animals. The fly seems to be well aware
that such skins will not oppose too much resistance, and seems to
know, also, that tender flesh is the most proper for supplying good
nourishment to its progeny. "And why," asks Réaumur, "should not the
instinct which conducts it to confide its eggs to the flesh of certain
species only, lead it to prefer the flesh of animals of the same
species which is most preferable?" The number of bumps which are found
upon a beast is equal to the number of eggs which have been deposited
in its flesh; or, to speak more correctly, to the number of eggs which
have succeeded, for apparently all are not fertile; but this number
is very different upon different cattle. Upon one cow only three or
four bumps may be observed, while upon another there will appear from
thirty to forty. They are not always placed on the same parts, nor
arranged in the same manner: commonly, they are near the spine, but
sometimes upon or near the thighs and shoulders. Sometimes they are at
remote distances from each other; at other times they are so near that
their circumferences meet. In certain places, three or four tumors may
be seen touching each other; and more than a dozen sometimes occur
arranged as closely together as possible.
It is very essential to the grub that the hole of the tumor should
remain constantly open; for by this aperture a communication with
the air necessary for respiration is preserved; and the grub is
thence placed in the most favourable position for receiving air. Its
spiracles for respiration, like those of many other grubs, are situated
immediately upon the posterior extremity of the body. Now, being almost
always placed in such a situation as to have this part above, or upon a
level with the external aperture, it is enabled to respire freely.[GT]
[Illustration: Bumps or wurbles produced on cattle by the Ox
breeze-fly.]
We have not so many examples of galls of this kind as we have of
vegetable galls; and when we described the surprising varieties of
the latter, we did not perceive that it was essential to the insects
inhabiting them to preserve a communication with the external air:
in the galls of trees, openings expressly designed or kept free for
the admission of air are never observed. Must the grub, then, which
inhabits the latter have less need of respiring air than the grub
of the breeze-flies in a flesh-gall? Without doubt, not; but the
apertures by which the air is admitted to the inhabitants of the
woody gall, although they may escape our notice, in consequence of
their minuteness, are not, in fact, less real. We know that, however
careful we may be in inserting a cork into a glass, the mercury with
which it is filled is not sheltered from the action of the air, which
weighs upon the cork; we know that the air passes through, and acts
upon the mercury in the tube. The air can also, in the same way,
penetrate through the obstruction of a gall of wood, though it have no
perceptible opening or crack; but the air cannot pass in this manner so
readily through the skins and membranes of animals.
In order to see the interior of the cavity of an animal gall,
Réaumur opened several, either with a razor or a pair of scissors;
the operation, however, cannot fail to be painful to the cow, and
consequently renders it impatient under the process. The grub being
confined in a tolerably large fistulous ulcer, a part of the cavity
must necessarily be filled with pus or matter. The bump is a sort of
cautery, which has been opened by the insect, as issues are made by
caustic: the grub occupies this issue, and prevents it from closing.
If the pus or matter which is in the cavity, and that which is daily
added to it, had no means of escaping, each tumor would become a
considerable abscess, in which the grub would perish; but the hole of
the bump, which admits the entrance of the air, permits the pus or
matter to escape; that pus frequently mats the hairs together which
are above the small holes, and this drying around the holes acquires a
consistency, and forms in the interior of the opening a kind of ring.
This matter appears to be the only aliment allowed for the grub, for
there is no appearance that it lives, like the grubs of flesh-flies,
upon putrescent meat. Mandibles, indeed, similar to those with which
other grubs break their food, are altogether wanting. A beast which
has thirty, forty, or more of these bumps upon its back, would be in a
condition of great pain and suffering, terrible indeed in the extreme,
if its flesh were torn and devoured by as many large grubs; but there
is every appearance that they do not at all afflict, or only afflict it
with little pain. For this reason cattle most covered with bumps are
not considered by the farmer as injured by the presence of the fly,
which generally selects those in the best condition.
A fly, evidently of the same family with the preceding, is described
in Bruce's 'Travels,' under the name of zimb, as burrowing during its
grub state in the hides of the elephant, the rhinoceros, the camel, and
cattle. "It resembles," he says, "the gad-fly in England, its motion
being more sudden and rapid than that of a bee. There is something
peculiar in the sound or buzzing of this insect; it is a jarring noise
together with a humming, which as soon as it is heard all the cattle
forsake their food and run wildly about the plain till they die, worn
out with fatigue, fright, and hunger. I have found," he adds, "some of
these tubercles upon almost every elephant and rhinoceros that I have
seen, and attribute them to this cause. When the camel is attacked
by this fly, his body, head, and legs break out into large bosses,
which swell, break, and putrefy, to the certain destruction of the
creature."[GU] That camels die under such symptoms, we do not doubt;
but we should not, without more minutely-accurate observation, trace
all this to the breeze-fly.
MM. Humboldt and Bonpland discovered, in South America, a species,
probably of the same genus, which attacks man himself. The perfect
insect is about the size of our common house-fly (_Musca domestica_),
and the bump formed by the grub, which is usually on the belly, is
similar to that caused by the ox breeze-fly. It requires six months to
come to maturity; and if it is irritated it eats deeper into the flesh,
sometimes causing fatal inflammations.
Grub Parasite in the Snail.
During the summer of 1829, we discovered in the hole of a garden-post,
at Blackheath, one of the larger grey snail shells (_Helix aspersa_,
Muller), with three white soft-bodied grubs burrowing in the body of
the snail. They evidently, from their appearance, belonged to some
species of beetle, and we carefully preserved them in order to watch
their economy. It appeared to us that they had attacked the snail
in its stronghold while it was laid up torpid for the winter; for
more than half of the body was already devoured. They constructed
for themselves little cells attached to the inside of the shell, and
composed of a sort of fibrous matter, having no distant resemblance
to shag tobacco, both in form and smell, and which could be nothing
else than the remains of the snail's body. Soon after we took them,
appearing to have devoured all that remained of the poor snail, we
furnished them with another, which they devoured in the same manner.
They formed a cocoon of the same fibrous materials during the autumn,
and in the end of October appeared in their perfect form, turning out
to be _Drilus flavescens_, the grub of which was first discovered in
France in 1824. The time of their appearance, it may be remarked,
coincides with the period when snails become torpid. (J. R.)
In the following autumn, we found a shell of the same species with a
small pupa-shaped egg deposited on the lid. From this a caterpillar was
hatched, which subsequently devoured the snail, spun a cocoon within
the shell, and was transformed into a small moth (of which we have not
ascertained the species) in the spring of 1830.
[Before concluding the account of the parasite insects, it will be
necessary to mention two of our British Ichneumonidæ, which not
only deposit their eggs in the larvæ of other insects, but make for
themselves cells of very beautiful structure. In the accompanying
illustration are shown the cells of one of our commonest and most
useful ichneumonidæ (_Microgaster glomeratus_), together with the
insect itself. At Fig. 1_a_ (p. 438) is shown the little insect of the
natural size, and the same is given at 1 much magnified.
This creature lays its eggs in the body of the cabbage caterpillar,
forty or fifty eggs being deposited in the same larva. They soon hatch
into little transparent grubs, which lie under the skin, and live on
the fatty parts of the caterpillar, which continues to grow, and seems
to thrive, whereas its bulk is largely made up of the ichneumon larvæ.
[Illustration: Microgaster glomeratus.]
After the caterpillar ceases from feeding, it crawls aside for the
purpose of assuming the pupal state. But, before it can do so, the
ichneumon larvæ, which have also ceased from feeding, burst their way
through the sides of the caterpillar, and immediately begin to spin
their cocoon. These are oval, very small, and covered with yellow silk.
A group of these cocoons is shown at Fig. 3. The innumerable fibres
of these cocoons hamper the caterpillars so much that, in most cases,
it seldom is able to stir from the spot, but dies in the midst of its
enemies. Groups of these yellow cocoons can be found in every wall
or paling near cabbage gardens. In a few days, the larvæ have passed
through their pupal stage, assuming the winged state, and emerge from
the cocoons through little circular doors, as seen in Fig. 2.
Our second illustration represents another species, _Microgaster
alveolarius_, together with its cocoons. As before, the insect is shown
of its natural size at la, and magnified at 1. The preliminary life of
this insect is exactly the same as that of the preceding; but, instead
of making a number of independent and separate cocoons, the insects
spin so closely together that they form an edifice very much resembling
a bee-comb. Fig. 5 represents one of these cell-groups of the natural
size, and the edge of another group is shown at Fig. 4. A longitudinal
section, slightly enlarged, is given at 3, in order to show the
hexagonal shape assumed by the aggregated cells; and Fig. 2 shows the
little lids which open to give egress to the insect. All these figures
are drawn from specimens in my collection.]
[Illustration: Microgaster alveolarius.]
THE END.
LONDON: PRINTED BY W. CLOWES AND SONS, STAMFORD STREET AND
CHARING CROSS.
FOOTNOTES:
[A] Stephens' Illustrations, vol. i., p. 72, note.
[B] Contemplation de la Nature, part ii. ch. 42.
[C] The original observations in this volume which are marked by the
initials J. R., are by J. Rennie, A.M., A.L.S., and those which are
enclosed in brackets are by the Rev. J. G. Wood, M.A., F.L.S.
[D] Introduction to Entomology, vol. i.
[E] Dunciad, book iv.
[F] Humboldt, Voyage, lib. vii., ch. 20.
[G] Amer. Ornith., i., p. 144.
[H] Amer. Ornith., iii., p. 21.
[I] Blumenbach; see also Insect Transformations, p. 231.
[J] Nomina si pereant, perit et cognitio rerum.
[K] J. R., in Mag. of Natural History, vol. i., p. 334.
[L] Miss Jermyn's Butterfly Collector, p. 11.
[M] Generally to ametabolous pupæ.
[N] See Spallanzani's Tracts, by Dalyell, vol. i.
[O] Ray, Hist. Insect., 254.
[P] The fifth order of Linnæus; insects with four transparent veined
wings.
[Q] Naturalist's Calendar, p. 100.
[R] Introduction to Entomology, vol. i. p. 435, 5th edit.
[S] See p. 50.
[T] Shapeless.
[U] The Owl observed by Vieillot in St. Domingo digs itself a burrow
two feet in depth, at the bottom of which it deposits its eggs upon a
bed of moss.
[V] American Ornithology, by Charles Lucien Bonaparte, vol. i. p. 69.
[W] Réaumur, vol. vi. bottom of page 182; Hist. of Selb. ii. 228; and
Introd. to Entomol. i. 504, 5th edition.
[X] In the Mag. of Nat. Hist. 1839, p. 458, Mr. Shuckard gives
an account of the nest of a wasp, which he regards as _Vespa
Britannica_,--remarkable for the material of which it was constructed,
and for the locality in which it was found. This nest, which was
exhibited at a meeting of the Entomological Society, was found near
Croydon, built in a sparrow's nest, and attached to the lining
feathers. "The smallness of the nest," says Mr. Shuckard, "and also
of the tier of cells, as well as the peculiar material of which it
appeared composed, led to a discussion, the tendency of which seemed to
support the opinion that it was most probably the nest of a _Polistes_,
a social-wasp not yet found in this country, but if not of _Polistes_,
certainly not yet determined or known." The nest was ovate, about an
inch and a half long, with a tier of cells internally, originating from
a common pedicle. It appeared to be constructed "of the agglutinated
particles of a soft white wood, probably willow, very imperfectly
triturated;" whence it had externally a rough granulated appearance. It
was sprinkled with black specks, arising perhaps from the intermixture
of more decayed portions of the wood; and was of a very fragile
texture. "The nature of the material, and its unfinished execution, as
well as the situation in which it was found, appear to me to be its own
peculiarities, and I must necessarily consider it merely an accidental
variation in material and locality from the usual nests of the _Vespa
Britannica_ of Leach."
[Y] Mémoires sur les Insectes, tom. vi., mem. vii. See also Bonnet
vol. ix.
[Z] It is right to remark that Huish and others have suggested that
the grubs thus royalized may originally be misplaced queens; yet
this admission is not necessary, since Madlle. Jurine has proved, by
dissection, the workers to be imperfect females.
[AA] Huber on Bees, p. 338.
[AB] Melisselogia, or Female Monarchy, 8vo., Lond. 1744.
[AC] De la Pluche, Spectacle de la Nature, vol. i.
[AD] Philosophical Trans. for 1792, p. 143.
[AE] Huber on Bees.
[AF] American Quarterly Review for June, 1828, p. 382.
[AG] Latreille, Mém. Acad. des Sciences, 1821.
[AH] Huber on Bees, p. 325.
[AI] From two Greek words [Greek: pro polis] meaning _before the city_,
as the substance is principally applied to the projecting parts of the
hive.
[AJ] Phil. Trans. for 1807, p. 242.
[AK] Schirach, Hist. des Abeilles, p. 241.
[AL] Kirby and Spence observed bees very busy in collecting propolis
from the tacamahaca-tree (_Populus balsamifera_).--Introd., ii. 186.
[AM] Huber on Bees, p. 408.
[AN] Philosophical Trans. for 1807, p. 242.
[AO] Spectacle de la Nature, tome i.
[AP] Huber on Bees, p. 358.
[AQ] Réaumur, vol. v., p. 380.
[AR] Huber on Bees, p. 368.
[AS] Huber on Bees, p. 220.
[AT] Memoirs of the Wernerian Nat. Hist. Soc., vol. ii. p. 260.
[AU] Bevan on Bees, p. 326.
[AV] Huber on Bees, p. 416.
[AW] Huber on Bees, p. 391.
[AX] From two Greek words, signifying _pitch_ and _wax_.
[AY] Huber on Bees, p. 415.
[AZ] Spectacle de la Nature, vol. i.
[BA] North American Rev., Oct. 1828, p. 355.
[BB] "Hibernia dives lactis ac _mellis_ insula."--Beda, Hist.
Eccles. i. 7.
[BC] Deut. xxxii. 13.
[BD] Psalm lxxxi. 16.
[BE] Forbes, Orien. Mem. i.
[BF] Amer. Q. Rev., iii. p. 383.
[BG] Roy. Mil. Chron. quoted by Kirby and Spence.
[BH] "Cantu querulæ rumpent arbusta cicadæ."--Georg. iii. 328.
[BI] A line is about the twelfth part of an inch.
[BJ] Introd., vol. i. p. 457.
[BK] Roesel, cl. ii., Pap. Nocturn., tab. xx. fig. 1, 2, 3, 4, 5, 6.
[BL] See p. 100.
[BM] Contemplation de la Nature, part XV. chap. 38.
[BN] A cement prepared of volcanic earth, or lava.
[BO] It is justly remarked by Réaumur, that when caterpillars are left
at liberty among their native plants, it is only by lucky chance they
can be observed building their cocoons, because the greater number
abandon the plants upon which they have been feeding, to spin up in
places at some distance. In order to see their operations, they must
be kept in confinement, particularly in boxes with glazed doors,
where they may be always under the eye of the naturalist. In such
circumstances, however, we may be ignorant what building materials we
ought to provide them with for their structures. A red caterpillar,
with a few tufts of hair, which Réaumur found in July feeding upon
the flower bunches of the nettle, and refusing to touch the leaves,
began in a few days to prepare its cocoon, by gnawing the paper lid
of the box in which it was placed. This, of course, was a material
which it could not have procured in the fields, but it was the nearest
in properties that it could procure; for, though it had the leaves
and stems of nettles, it never used a single fragment of either. When
Réaumur found that it was likely to gnaw through the paper lid of the
box, and might effect its escape, he furnished it with bits of rumpled
paper, fixed to the lid by means of a pin; and these it chopped down
into such pieces as it judged convenient for its structure, which
it took a day to complete. The moth appeared four weeks after, of a
brownish-black colour, mottled with white, or rather grey, in the
manner of lace.
Bonnet also mentions more than one instance in which he observed
caterpillars making use of paper, when they could not procure other
materials.
[BP] Kirby, in 'Linn. Trans.,' vol. v. p. 246, and Introd. ii.
[BQ] See Fig. _d_, p. 238.
[BR] Réaumur, 'Mém. Hist. Insectes,' iii. 70.
[BS] 'Contemplation de la Nature,' part xii. chap. x. note.
[BT] 'Animal Biography,' vol. iii. p. 330, Third Edition.
[BU] Bonnet, xi. p. 204; Kirby and Spence, 'Introduction,' i. 464,
Fifth Edition.
[BV] Bonnet, vol. ix. p. 203.
[BW] 'Mém. Hist. Insect.' iii. p. 106.
[BX] Réaumur, iii. p. 130.
[BY] Bonnet, 'Contempl. de la Nature,' part xii.
[BZ] Swammerd., 'Book of Nature,' vol. ii. p. 84.
[CA] 'Contempl. de la Nature,' part xii. p. 197.
[CB] Bonnet, 'Observ. sur les Insectes,' vol. ii. p. 425.
[CC] Dict. Classique d'Hist. Nat. Art. Grillon.
[CD] Natural History of Selborne, ii. 82.
[CE] Entomologie, par R. A. E. 18mo., Paris, 1826, p. 168.
[CF] Natural History of Selborne.
[CG] Act. Acad. Berolin. 1752, et Gleditsch, Phys. Botan., quoted by
Kirby and Spence, ii. 353.
[CH] Moufet, 153. Kirby and Spence, ii. 350.
[CI] Journal of a Naturalist, p. 311.
[CJ] Bingley, Anim. Biog., vol. iii, p. 230.
[CK] Phil. Trans., vol. xliv. p. 579.
[CL] Anim. Biog., vol. iii. p. 233.
[CM] Anderson's Recr. in Agricult., vol. iii. p. 420.
[CN] Hints, p. 74.
[CO] Journal of a Naturalist, p. 304.
[CP] A line is the twelfth part of the old French inch. _See_ Companion
to the Almanac for 1830, p. 114.
[CQ] M. P. Huber on Ants, p. 20.
[CR] Stedman's Surinam, vol. i. p. 160.
[CS] M. P. Huber on Ants, p. 23.
[CT] Latreille, Hist. Nat. des Fourmis.
[CU] Dr. Cleghorn, Thesis de Somno.
[CV] Aristotle Hist. Animal. ix. 38. Pliny says, "Operantur et noctu
plenâ lunâ; eadem interlunio cessant," _i.e._, They work in the night
at full moon, but they leave off between moon and moon. It is the
latter that we think doubtful.
[CW] M. P. Huber on Ants, p. 31.
[CX] Huber on Ants, p. 43.
[CY] In formicâ non modo sensus, sed etiam mens, ratio, memoria.
[CZ] Aldrovandus de Formicis, and Johnston, Thaumaturg. Nat. p. 356.
[DA] See Professor Paxton's Illustrations of Scripture, i. 307.
[DB] Huber on Ants, p. 15.
[DC] Huber on Ants, p. 11.
[DD] Huber, p. 56.
[DE] The acid of ants.
[DF] Huber.
[DG] Hawkesworth's Account of Cook's First Voyage.
[DH] Phil. Trans., xxx. p. 346.
[DI] Jobson's Gambia, in Purchas's Pilgrim, ii. p. 1570.
[DJ] Heber's Journal, vol. i. p. 248.
[DK] Smeathman, in Phil. Trans., vol. lxxi.
[DL] Smeathman.
[DM] Quoted by De Geer, vol. vii.
[DN] Hist. Nat. Générale, vol. xiii. p. 66.
[DO] Smeathman, in Phil. Trans., vol. lxxi. p. 169, note.
[DP] Latreille, Hist. Nat. Générale, tom. xiii. p. 64.
[DQ] Lyonnet.
[DR] Spectacle de la Nature, vol. i.
[DS] Cours d'Agriculture, par M. Rozier. Paris, 1801.
[DT] This is denied by recent observers.
[DU] Spectacle de la Nature, vol. i.
[DV] Count Dandolo's Art of Rearing Silk-Worms, Eng. Transl., p. 215.
[DW] On a tort de croire que le bruit nuise à ces insectes, Hist. Nat.
Générale, vol. xiii. p. 170.
[DX] Shaw's Gen. Zoology, vol. vi.
[DY] North American Review, Oct. 1828, p. 449.
[DZ] Essay on the Silk-Worm, p. 95. London, 1719.
[EA] Preface to Dandolo on the Silk-Worm, Eng. Transl., p. xiii.
[EB] Glover's Directory of the County of Derby, Introd., p. xvi.
[EC] Memecken, quoted by Kirby and Spence, iii. 280.
[ED] Brahm's Ins. Nat. 289, and Kirby and Spence's Intr. iii, 223.
[EE] De Geer, Mém. i. 319.
[EF] Curtis, Hist. of Brown-tail Moth, 4to. London, 1782.
[EG] Réaumur, ii. p. 137.
[EH] Salisbury, Hints on Orchards, p. 53.
[EI] Hardy's Travels in the Interior of Mexico, p. 32.
[EJ] Hill's Swammerdam, part i. p. 23.
[EK] Swammerdam, part i. p. 24.
[EL] Intr., vol. i. p. 415.
[EM] Kirby and Spence, vol. i. Intr. p. 416.
[EN] Porcupines do not shoot out their quills, as was once generally
believed.
[EO] Lister, Hist. Animalia Angliæ, 4to. p. 7.
[EP] Phil. Mag., ii. p. 275.
[EQ] Vol. i. Intr., p. 417.
[ER] Phil. Mag.,, ii. p. 339.
[ES] Nat. Hist. of Selborne, vol. i. p. 327.
[ET] Book of Nature, part i. p. 25.
[EU] Hist. Anim. Angliæ, 4to.
[EV] Mémoires, vol. vii. p. 189.
[EW] Spectacle de la Nature, vol. i.
[EX] Book of Nature, part i. p. 25.
[EY] Animal Biography, vol. iii. p. 475, 3rd edition.
[EZ] Brez, Flore des Insectophiles. Notes, Supp. p. 134.
[FA] Thomson's Ann. of Philosophy, vol. iii. p. 306.
[FB] Loudon's Mag. of Nat. Hist., vol. i. p. 322.
[FC] Experim. Researches in Nat. Hist., p. 136.
[FD] Mag. Nat. Hist., vol. i. p. 324.
[FE] Linn. Trans., vol. xv. p. 456.
[FF] Mag. Nat. Hist., vol. ii. p. 397.
[FG] Linn. Trans., vol. xv. p. 453.
[FH] "----L'un des bouts de ces premiers fils, afin que le vent ou
un courant d'air pousse l'autre extrémité de l'un d'eux au de là de
l'obstacle."--Dict. Classique d'Hist. Nat., vol. i. p. 510.
[FI] Evelyn's Travels in Italy.
[FJ] Book of Nature, part i. p. 24.
[FK] Bloomfield's Remains, vol. ii. p. 64, _note_.
[FL] Animal Biography, iii. 470-1.
[FM] Mém. de l'Acad. des Sciences pour 1707, p. 339.
[FN] Kirby and Spence, Intr. i. 419.
[FO] Darwin's Zoonomia, i. 253, 8vo. ed.
[FP] Mém. Soc. d'Hist. Nat. de Paris, An. vii.
[FQ] Mém. Soc. d'Hist. Nat. de Paris, p. 125, and Latreille, Hist. Nat. Géuér. viii. p. 163.
[FR] Kirby and Spence, Intr. i. 425.
[FS] Aranei Suecici, Stockholm, 1757.
[FT] Mém. des Araign. Aquat., 12mo. Paris, 1799.
[FU] Clerck, Aranei Suecici, cap. viii.
[FV] De Geer, Mém. des Insectes, vii. 312.
[FW] Spectacle de la Nature, i. 58.
[FX] Linn. Trans. vol. xv.
[FY] Spectacle de la Nature, i. p. 61.
[FZ] Remains, ii. 62-5. It is a remarkable fact, as recorded from
personal observation by Mr. Bell (British Reptiles), that the toad
swallows the cuticle detached from its body during the moult which it
undergoes.
[GA] Spectacle de la Nature, i. 119.
[GB] Introduction, ii. 449.
[GC] Hist. des Moeurs et de l'Instinct, vol. ii.
[GD] Entomologie, par R. A. E., p. 242. Paris, 1826.
[GE] Elements of the Philosophy of Plants, Eng. Trans., p. 285.
[GF] Flore Franç. Disc. Préliminaire.
[GG] Réaumur, vol. iii.
[GH] In order to prevent ambiguity, it is necessary to remark that the
excrescences thus called must not be confounded with the true galls,
which are occasionally found in the gall-bladder.
[GI] Réaumur, Mém. iv. 505.
[GJ] Mém. iv. 538.
[GK]
Est lucos Silari circa ilicibusque virentem
Plurimus Alburnum volitans, cui nomen asilo
Romanum est, Oestrum Graii vertere vocantes,
Asper, acerba sonans; quo tota exterrita silvis
Diffugiunt armenta; furit mugitibus æther
Concussus, sylvæque et sicci ripa Tanagri.
_Georg._ lib. iii. 146.
[GL] Linnæus, Lachesis Lapponica, July 19th.
[GM] Linnæus, Flora Lapponica, p. 378, ed. Lond. 1792.
[GN] Kirby and Spence, Introd. i. 151.
[GO] Kirby and Spence, p. 149.
[GP] These circumstances afford, we think, a complete answer to
the query of Kirby and Spence--"There can be little doubt (or else
what is the use of such an apparatus?) that it bores a hole in the
skin."--Introd. i. 162, 2nd edit.
[GQ] Linn. Trans. iii. 305.
[GR] Linn. Trans. iii. 305.
[GS] Mém. iv. 540.
[GT] Réaumur, iv. 549.
[GU] Bruce's Travels, i. 5, and v. 191.
Transcriber's Note
The unmatched opening quote on page 12 was assumed to be a
typographical error and removed. Where a sequential series of
paragraphs have an opening bracket without a closing one, these were
standardized to one opening and one closing bracket for the whole
section. One opening bracket missing on page 38 was assumed to belong
at the start of last line of that paragraph. The closing quote from the
second paragraph on page 47 was added. An Internet search confirmed
this location.
Where the footnotes originally stated "Ibid.", the source of the
previous footnote was inserted.