The Neuroptera--the type of which order are the _Libellulæ_, or Dragon
Flies--have four membranous wings, generally rather broad, provided
with transverse delicately reticulated nervures, which gives them the
appearance of lace. Although one of the least extensive, this Order
presents the greatest modifications of form and of habits.
One section of Neuroptera contains some insects which undergo
incomplete metamorphoses. The _Libellulæ_, the _Ephemeræ_, and the
_Termites_, belong to this category. The insects belonging to the
other section, in which are classed the _Phryganidæ_,[109] or Caddis
Flies, the _Panorpatæ_, and the _Myrmelionides_, or Ant Lions, undergo
complete metamorphoses. The pupæ of the first walk and live absolutely
in the same way as the larvæ; only, at the moment of the last
transformation, the skin of the pupa splits, and the perfect insect
comes forth. In the case of the second, on the contrary, the pupa is
motionless, inactive, and takes no food, as in the Hymenoptera,
Coleoptera, &c. In spite of this diversity in their mode of
development, all these insects resemble each other too much for us to
divide the Order; from which it follows that we must not attach too
much importance to differences of transformation by which the insect
arrives at its perfect state.
[109] These were separated from the Neuroptera and made a
separate order, under the name of Trichoptera, by Kirby.--ED.
The most interesting insects among the Neuroptera are the _Termites_,
improperly called White Ants, on account of the great analogy which
exists between their habits and those of ants. They constitute, by
their way of living, a striking anomaly in the order in which their
conformation places them. In fact, they live in very numerous societies,
and build very solid and very extensive dwelling-places--quite
Cyclopean or Titanic works in comparison to the tiny dimensions and
weak and feeble appearance of the insect. (PLATE IX.)
[Illustration: IX. Nests of White Ants.]
Many travellers have spoken of these insects. They are met with in the
savannahs of North America, in Guyana, in Africa, in New Holland, and
even in Europe, whither they have been imported. M. de Prefontaine
relates that, when he was travelling in Guyana, he saw the negroes
besieging certain strange buildings, which he calls ant-hills. They
dared not attack them, except from a distance, and with fire-arms,
although they had taken the precaution of digging all round them a
little fosse filled with water, in which the besieged would be drowned
if they made a sortie. These were the termites' nests.
Perhaps it is to termites Herodotus alludes when he speaks of ants
which inhabit Bactria, and which, larger than a fox, eat a pound of
meat a day.[110] Retired in the sandy deserts, these gigantic insects
hollow out (says he) subterranean dwellings, and raise mounds of
golden sand, which the Indians carry away at the peril of their lives.
Pliny, who relates the same fables, adds that there were to be seen in
the Temple of Hercules the horns of these ants. Even in our own days
some travellers have repeated absurd fables about termites. They have
attributed to them a venom which one cannot breathe without being
poisoned; they have said that a single bite was enough to cause a
mortal fever. The truth, as it is revealed to us by conscientious
observers, is still stranger than these fictions or errors. The
termites present curious modifications, on the nature of which
naturalists are not agreed. There are, in the first place, the perfect
insects, males and females, which are provided with wings; then there
are the neuters, which are divided into _soldiers_, whose duty it is
to defend the nest, and into _workers_, upon whom devolve the
architectural works and household cares. These last are smaller than
the soldiers. Latreille and some other naturalists think that these
workers are the larvæ of the termites. Smeathman thinks that the
soldiers are the pupæ. M. de Quatrefages admits that the soldiers are
the neuters, and that the workers are recruited both from the larvæ
and from the pupæ. It may be admitted, with other naturalists, that
the soldiers and the workers are neuters: the first, abortive males;
the second, abortive females. Here is, indeed, what M. Lespès has
observed in the termites of the Landes. Among these insects, the most
numerous are the workers: their size is that of a large ant, and their
duties are to excavate galleries, to search for provisions, and to
take care of the eggs, the larvæ, and the pupæ. The workers have a
rounded head and short mandibles, and are blind. The soldiers, less
numerous, have an enormous head--nearly as big as the rest of their
body--very strong, crossed mandibles, and are blind like the workers.
Anatomy showed M. Lespès that both are _neuters_--that is, the
soldiers, males, and the workers, females--with aborted organs.
[110] De Quatrefages, "Souvenirs d'un Naturaliste," tome ii.,
p. 377. In 18mo. Paris, 1854.
The larvæ of the females much resemble the workers. Those which are to
become males or females are distinguished from those which are to
become neuters by very slight rudiments of wings, and their pupæ show
already imperfect wings, hidden in cases; furthermore, they have eyes
hidden under the skin. The males and females alone have eyes; they
also have wings, which they lose immediately after the coupling. Those
which proceed from the pupæ with long wing cases become small kings
and queens after their swarming, which takes place at the end of May.
The pupæ with short wing-cases become perfect in the month of August,
and produce larger males and females, which become kings and queens.
All these couples are collected by the neuters; and the queens, large
and small, set to work immediately to lay. The largest are much the
more fruitful. The workers do not seem to take any care of them at
all. With the exception of this last peculiarity, everything probably
goes on in the same manner with the exotic termites; but with the
latter the queen is an object of worship.
Fig. 383 represents the four types of the republic of the _Termes
lucifugus_. On the left is a worker, on the right a soldier, in the
centre a winged male, all three very much magnified, the lines drawn
by their side showing the natural size. Below the male is the pregnant
queen (D D D D), of a species of which we are about to speak, of the
natural size.
Many species of termites were studied with care by the English
traveller, Smeathman, at the end of the last century, in Southern
Africa. His account of them is the most exact and most complete which
we have of these insects.[111] The largest of the species observed is
the _Termes bellicosus_. The workers are a fifth of an inch long, the
body soft, and of an extreme delicacy, but the sharp mandibles capable
of attacking the hardest bodies. The soldiers are twice as long, and
weigh as much as fifteen workers, and may be distinguished by their
enormous horned head, armed with sharp pincers. The male weighs as
much as thirty workers, and attains to a length of nearly four-fifths
of an inch.
[111] "Some Account of the Termites," &c., in the
_Philosophical Transactions_, vol. lxxi. 1781.
[Illustration: Fig. 383.--Termes lucifugus. Male (A), Worker (B),
Soldier (C), magnified. Fecundated female of _Termes bellicosus_,
natural size, surrounded by workers (D D D D).]
But the pregnant female leaves all these dimensions far behind. Her
abdomen becomes two thousand times as big as the rest of her body!
She then attains to six inches in length, and weighs as much as thirty
thousand workers. By a hideous contrast, the head alone does not
increase in size. D D D D (Fig. 383) is an exact representation of
this monster. She is always motionless and captive in her cell,
entirely occupied in laying. Her fecundity surpasses all bounds: sixty
eggs a minute, more than 80,000 a day. Smeathman is inclined to think
that this prodigious laying goes on during the whole of the year.
"This soft, whitish beast," says M. Michelet, "a belly rather than a
being, is as large, at least, as one's thumb; a traveller professes to
have seen one of the size of a crawfish. The larger she is, the more
fruitful, the more inexhaustible, this terrible insect-mother seems to
be the more adored by the fanatical rabble. She seems to be their beau
ideal, their poetry, their enthusiasm. If you carry away with any
rubbish a portion of their city, you see them instantly set to work at
the breach to build an arch which may protect the venerated head of
the mother, to reconstruct her royal cell, which will become (if there
are sufficient materials) the centre, the base of the restored city. I
am not astonished, though, at the excessive love which this people
show for this instrument of fecundity. If all other species did not
combine to destroy them, this truly prodigious mother would make them
masters of the world, and--what shall I say?--its only inhabitants.
The fish alone would be left; but insects would perish. It suffices to
be remembered that the mother-bee does not produce in a year what the
female white ant can produce in a day. By her they would be enabled to
devour everything; but they are weak and tasty, and so everything
devours them."[112] In fact, birds are very greedy after termites;
poultry destroy immense quantities of them. Ants give chase to them
and eat them by legions. The negroes in Southern Africa cannot be
sated with them. They gather such as have fallen into the water, and
roast them like coffee; thus prepared, they eat them by handfuls, and
find them delicious. The Indians smoke the termites' nests, and catch
those that have wings. They knead them up with flour, and make a sort
of cake of them. Travellers, moreover, all agree in speaking of them
as very nice food, comparing their flavour to that of marrow or of a
sugared cream. Smeathman prefers them to the famous palm worm (_ver
palmiste_ of the colonists), a delicacy known in South America, which
is the larva of the _Calandra palmarum_, a species of beetle. It
seems, however, that an abuse of fried termites brings on a dysentery
which may prove mortal.
[112] J. Michelet, "L'Insecte," p. 328.
[Illustration: X. Nest of the White Ant (_Termes bellicosus_), in
Central Africa, after Smeathman. 1. Male. 2, 4, 5. Neuters. 3. Gravid
Female.]
All the species of termites are miners, but the greater number are
also architects and masons. A few make their nests round a branch of a
tree. This nest is of enormous dimensions: it is as large as a tun.
The illustration (PLATE X.)--after a drawing in Smeathman's
work--shows a nest of the _Termes bellicosus_, composed of bits of
wood firmly stuck together with gum. Above their subterranean
galleries the greater part of termites construct vast edifices, which
contain their magazines and nurseries. The _Termes mordax_ and _Termes
atrox_ raise perfect columns, surmounted by capitals which project
beyond them and give them the appearance of monstrous mushrooms. These
columns attain a height of twenty inches, with a diameter of five;
they are constructed with a black clay, which, worked up by the
insects, acquires great hardness. The interior is hollow, or rather
perforated with irregular cells; but the most curious edifices are
those of _Termes bellicosus_. These are irregularly conical mounds,
flanked by a certain number of turrets, decreasing in height.
Smeathman gives them a height of from ten to twelve feet; but
Jobson[113] affirms that he has seen some as high as twenty feet. If
men constructed monuments so disproportionate to their size, the great
pyramid of Giseh, instead of being 146 mètres in height, would be
1,600, and would be higher than the Puy-de-Dôme!
[113] "History of Gambia."
These knolls of earth are of a solidity which will bear any trial. Not
only can many men mount on them without shaking them, but buffaloes
establish themselves upon them as watch-towers, from which they can
see over the high grass which covers the plain, if the lion or the
panther is threatening them. These edifices are hollow; but their
sides are from fifteen to twenty inches thick, and are as hard as a
rock. They are hollowed out into galleries, which connect them with
the underground dwelling. Under the dome is a pretty large vacant
space, a sort of top storey or attic, occupying one-third of the total
height, and which keeps up in the edifice a more uniform temperature
than if all the block had been filled up. On a level with the ground
is the royal cell, oblong, with a flat floor and a rounded ceiling,
and pierced with round windows. All round are distributed the offices;
they are rooms also with rounded and vaulted ceilings, communicating
with each other by corridors. On the sides rise the magazines, with
their backs placed against the walls of the house; they are filled
with gums and with vegetable juices solidified and in powder. On the
ceiling of the royal chamber rise pillars of about two feet in
height, which support the egg rooms. These are little cells with
partitions of saw-dust stuck together with gum, which separate at the
opening the large chambers from the clay halls. Placed between the
attics and the great nave surmounting the royal hall, the nursery is
in the most desirable position possible for uniformity of temperature
and for ventilation.
The royal cell encloses a unique couple, objects of the most assiduous
attentions, but kept in closest captivity, for the doors are too
narrow to afford a passage to the monstrous queen, and even to the
male, who keeps generally crouching by her side. Thousands of servants
busy themselves round the mother; they feed her and carry away, night
and day, the myriads of eggs which she lays. The eggs are placed in
the egg houses, where they give birth to white larvæ, resembling the
workers, which nourish themselves at first on a sort of mouldy fungus
which grows on the partitions of their cells. They then become pupæ,
then neuters, or males and females, the last two being provided with
wings.
On a stormy evening the males and females come out of their nest by
millions to couple in the air; then immediately afterwards they fall
to the ground and lose their wings, when they become an easy prey to
their enemies. A few couples only, picked up by the workers, are put
under shelter, and become the nucleus of a new colony. The soldiers
have no other occupation but to defend the nest. If man attacks them,
at the first blow with the pick-axe they are to be seen running out
furiously. They attack their aggressors, pierce them till they bring
blood, and with their sharp pincers hang on to the wound, and allow
themselves to be torn to pieces rather than leave go their hold. The
negroes who have no clothes are soon put to flight; Europeans only get
off with their trousers very much spotted with blood. During the
combat, the soldiers strike from time to time on the ground with their
pincers, and produce a little dry sound, to which the workers answer
by a sort of whistling. The workers immediately make their appearance;
and with their pellets of mortar set to work to stop up the holes, and
to repair the damage. The soldiers then re-enter, with the exception
of a small number, who remain to superintend the work of the masons;
they give, at intervals, the usual signal, and the workers answer by a
whistling which means, "Here we are!" as they redouble their activity.
If the attack recommences, the soldiers are at their posts, defending
the ground inch by inch. During this time the workers mask the
passages, stop up the galleries, and wall up with care the royal cell.
If you manage to penetrate as far as this sanctuary, you may pick up
and carry away from the cell which contains them the precious couple
without the workers in attendance on them interrupting their work, for
they are blind.
They never venture in sight except in extreme cases. No one is
ignorant of the terrible destruction these insects occasion to the
works of man. Invisible to those whom they threaten, they push on
their galleries to the very walls of their houses. They perforate the
floors, the beams, the wood-work, the furniture, respecting always the
surface of the objects attacked in such a manner that it is impossible
to be aware of their hidden ravages. They even take care to prevent
the buildings they eat away from falling by filling up with mortar the
parts they have hollowed out. But these precautions are only employed
if the place seems suitable, and if they intend to prolong their
sojourn there. In the other case they destroy the wood with
inconceivable rapidity. They have been known, in one single night, to
pierce the whole of a table leg from top to bottom, and then the table
itself; and then, still continuing to pierce their way, to descend
through the opposite leg, after having devoured the contents of a
trunk placed upon the table. On account of the devastations which they
occasion, Linnæus has called the white ant the greatest plague of the
Indies.
There exist in France two species of termites, the _Termes lucifugus_,
a little insect of a brilliant black (at least in the male), with
russety legs, which is common enough in the moors of Gascony; and the
Yellow-necked White Ant (_Termes flavicollis_), which lives in the
interior of trees and does a great deal of mischief in Spain and in
the south of France to olive and other precious trees, whilst the
first attacks oak and fir trees. Latreille established that it is the
_Termes lucifugus_ which causes such havoc at La Rochelle, at
Rochefort, at Saintes, at Tournay-Charente, in the Isle of Aix, &c.,
where many houses have been completely undermined by these terrible
insects. But M. de Quatrefages[114] has proved that the habits of the
termes found in towns differ in many essential points from the habits
of termes in the country. And so it is most probable that the former
belong to an exotic species, which must have been unfortunately
imported into France by a merchant vessel. According to M.
Bobe-Moreau,[115] it was only in 1797 that termites were discovered
for the first time in Rochefort, in a house which had stood for a long
while uninhabited, and which they had completely undermined. In 1804,
Latreille relates, as a "hearsay," that the termites had for some
years made the inhabitants of Rochefort uneasy; but in 1829 the same
author tells a very different tale. He speaks with dismay of the
ravages committed by this insect in the workshops belonging to the
Royal Navy. The importation of the termes into France is then of
recent date. A note which was sent to M. de Quatrefages by M.
Beltrémieux, fixes with still greater accuracy the date of the
importation of the termites; it must have taken place about 1780, a
period at which the brothers Poupet, rich shipowners, caused bales of
goods to come from St. Domingo to Rochefort, to La Rochelle, and to
other places in that neighbourhood which possess storehouses. The
ravages which the termites have committed in the towns of La Saintonge
are really frightful. Like Valencia, in New Granada, these towns will
find themselves one of these days suspended over catacombs. At
Tournay-Charente, the floor of a dining-room fell in, and the
Amphytrion and his guests tumbled together in the cellar. There may be
seen in the galleries of the Museum of Natural History of Paris the
wooden columns which supported this room, and which were preserved by
Audouin, who had been sent on a mission to report on the damages done.
Audouin also selected, as an object of curiosity, a lady's bridal
veil, which had been entirely riddled with holes by the termites.
[114] "Note sur les Termites de la Rochelle." _Annales des
Sciences Naturelles_, 3e série, tome xx., p. 18. 1853.
[115] "Mémoire sur les Termites observés à Rochefort." Saintes,
1843.
At La Rochelle these insects took possession of the Prefect's house
(built by the brothers Poupet), and of the Arsenal. There they invaded
offices, apartments, court, and garden. They could not drive in a
stake, or leave a plank in the garden, but it was attacked the next
day. One fine morning the archives of the department were found
destroyed, without there being the smallest trace of the damage to be
seen on the exterior. The termites had mined through the wood-work,
pierced the cardboard, eaten up the parchments and the papers of the
administration, but had always scrupulously respected the upper leaf
and edges of all the leaves. It was by mere chance that a clerk, less
superficial than his colleagues, one fine day raised one of the leaves
which hid this _detritus_, and thus discovered the destruction of the
archives. All the papers of the Prefecture are now shut up in boxes of
zinc.
These termites do not venture, any more than their congeners, into the
light of day. These terrible miners always envelop themselves in
obscurity, and construct on all sides covered galleries as they
advance into a building. M. Blanchard and M. de Quatrefages saw in La
Rochelle the galleries made by them. They are tubes formed of
agglutinated material, which are stuck along the walls in the cellars
and the apartments, or else suspended to the roof like stalactites.
Certain parts of Agen and of Bordeaux begin also to suffer from the
ravages of these insects. The danger appears to be imminent.
We are indebted to M. de Quatrefages for some interesting experiments
on the termites of La Rochelle. Not only has the learned naturalist
helped to make known to us the habits of these dark-loving insects,
but he has also told us how to destroy them. Different substances have
been tried in vain to stop these terrible ravages--essence of
turpentine, arsenical soap, boiling lye, &c. M. de Quatrefages had
recourse to gaseous injections. He tried successively binoxide of
nitrogen, nitric acid, chlorine and sulphurous acid; chlorine, above
all, fully answered his hopes. With pure chlorine he killed the
termites instantaneously; mixed with nine-tenths of air, he suffocated
them in half an hour. "For attacking the termites," says M. de
Quatrefages, "one ought to choose by preference the period of their
reproduction, so as to destroy the pregnant females. It is probable
that, like their exotic congeners, the termites of France will
endeavour to defend themselves by walling up the interior of their
galleries at the first signs of an attack. The operator must then act
with a great deal of promptitude, and direct the apparatus as much as
possible into the very centre of their habitation, where the galleries
are the broadest and the most numerous.
"With whatever care one acts, and whatever may be the success of a
first attempt, it seems to me impossible to destroy in one campaign
all the termites of a locality. In this, as in all operations of the
same kind, a certain amount of perseverance is necessary, especially
if it is in a town or in a country infested by them to a very great
degree; in that case one will be forced to repeat the operation from
time to time. When, on the contrary, the termites are already
cantoned, it seems to me that the success ought to be lasting. This is
fortunately the case at La Rochelle; and by knowing how to profit by
it, one may doubtlessly prevent the spread of these pests, which at
one time or another, may attack the whole town."[116]
[116] "Mémoires sur la destruction des Termites." _Annales des
Sciences Naturelles_, 3e série, tome xx., p. 15.
In 1864 the Lords of the English Admiralty addressed an inquiry to the
Entomological Society of London, on the best means of preserving wood
from the attacks of the Indian termites. In answer to this inquiry,
the Entomological Society recommended many processes: the injection
of quicklime or of creosote, the application of arsenical soap, &c.
But it does not appear that these processes are infallibly
efficacious, nor, above all, easy to employ.
[Illustration: Fig. 384.--Larva of Perla bicaudata.]
[Illustration: Fig. 385.--Larva of a Nemoura.]
[Illustration: Fig. 386.--Perla marginata (larva).]
Among other Neuroptera which undergo incomplete metamorphoses, we may
mention, first, the genera _Perla_ and _Nemoura_,[117] (Figs. 384,
385, and 386), which flutter about the banks of rivers, and settle on
stones, shrubs, and aquatic plants. Their larvæ are naked, without
cases, and always live in the water, hiding themselves under stones,
to watch for small insects, for they are carnivorous. One sees them
often balancing their bodies, holding on to a pebble. They go through
the winter, and only become pupæ in the spring. After moulting, they
have the rudiments of wings. Very soon afterwards the pupæ leave the
water, and undergo their metamorphosis. The adult lives only a few
days, for its mouth is not suited for receiving food. The larvæ have,
at the end of their bodies, two long threads, which remain in the
perfect _Perla_, but not in the perfect _Nemoura_; the latter lose the
two caudal hairs when they arrive at the adult state. One species of
_Perla_ is very common on the quays of Paris.
[117] From [Greek: nêma], a thread; and [Greek: oura], a
tail.--ED.
[Illustration: Fig. 387.--Perla bicaudata.]
[Illustration: Fig. 388.--Nemoura variegata.]
[Illustration: Fig. 389.--Nemoura variegata (larva).]
The _Ephemeridæ_, or May-Fly family, have long, slender bodies,
provided with two or three long silky hairs. Their name indicates the
short duration of their existence. They appear in great numbers at
certain seasons of the year. Their hatching takes place at sunset;
they have coupled and laid their eggs by sunrise next day, and have
ceased to live; so that the banks of rivers, of ponds, of lakes, are
strewed with their bodies. Their number is sometimes so considerable
that, according to Réaumur, the soil seems as if it were covered with
snow, and they are gathered up for manure. The common Ephemera, or
May-Fly (_Ephemera vulgata_, Fig. 390), is of a brown colour, banded
with yellow, and the wings smoky, with brown spots. These insects are
remarkable for their elegant flight; they are continually rising and
falling. When they move their wings they rise; but if their wings,
though spread out, remain motionless, as also the silky hairs which
form their tail, they fall again. They may be seen in myriads in
places where there is much water.
[Illustration: Fig. 390.--Ephemera vulgata, imago.]
We have said that the _Ephemeræ_ live only for a few hours. This is
the general rule; but their existence can be prolonged for ten or
fifteen days by preventing their copulation. If, however, the duration
of the life of these insects is so short when they have reached the
perfect state, and when the conformation of the mouth prevents them
from taking any nourishment, their larvæ state is of very long
continuance. Swammerdam says, in his curious Memoir, entitled "Vita
Ephemeri," it is not less than three years.
The females lay their eggs in one single mass, and let them fall into
the water, in the form of a packet. The larvæ which come out of them
are very active, and swim with great ease; but generally conceal
themselves under the pebbles at the bottom. The sides of their abdomen
are provided with gills, very much fringed, which serve them, not only
for breathing the air under the water in the same way that fish do,
but also for swimming. The larvæ have, at the extremity of their body,
two or three hairs, like the perfect insect. They hollow out galleries
in the beds of rivers and ponds, and live on small insects. The pupa
(Fig. 392) differs only from the larva (Fig. 391) in having the
rudiments of wings. When about to undergo their metamorphosis, they
come out of the water and cling to plants, &c. The skin cracks on the
back when it is dry, and there comes out a heavy insect, which flies
feebly, and has opaque wings. It is still enveloped in a very thin
skin, of which a last moult, after a few hours, frees it. This skin
remains sticking to the plant on which the moulting was effected,
preserving the shape of the insect. This moult is peculiar to the
_Ephemeræ_; it is the transition from the false imago (pseudo-imago)
to the imago.
[Illustration: Fig. 391.--Larva of an Ephemera.]
[Illustration: Fig. 392.--Pupa of an Ephemera]
In the same family is the genus _Cloëon_, whose larvæ prey on minute
insects. The _Cloëon diptera_ (Fig. 393), which has only two wings, is
often to be met with in houses, resting on the window panes and
curtains. All these insects keep badly in collections; they lose their
shape, and their members are so fragile that the least shock suffices
to break them.
The _Libellulas_, or Dragon-Flies, are insects of a well-defined type.
The elegance of their shape, the grace of their movements, have won for
them among the French their common appellation of "Demoiselles." They
are always of largish size. Many are of bright and metallic colours,
which are not inferior in beauty to those of butterflies. Their wings,
of an extreme delicacy, always glossy and brilliant, present varied
tints; sometimes they are completely transparent, and have all the
colours of the rainbow. Often, the colour of the males differs from that
of the females. They may be seen fluttering about on the water during
the whole summer, especially when the sun is at its highest. They fly
with extreme rapidity, skimming over the water at intervals, and
escaping easily when one wishes to catch them. Nothing is prettier than
a troop of dragon-flies taking their sport on the side of a pond or on
the banks of a river, on a fine summer's day, when a burning sun causes
their wings to shine with most vivid colours.
[Illustration: Fig. 393.--Cloëon diptera.]
In the perfect state, as well as in that of the larva and the pupa,
the _Libellulæ_ are carnivorous. Their rapid flight makes them expert
hunters, and their enormous eyes embrace the whole horizon. They
seize, while on the wing, flies and butterflies, and tear them to
pieces immediately with their strong mandibles. Sometimes, the ardour
of the chase leading them on far from the streams, they are met with
in the fields. The female lays her eggs in the water, from which
emerge larvæ which remind one somewhat of the form of the insect, only
their body is more compact and their head flattened. The larvæ and
pupæ inhabit the bottom of ponds and streams, where, keeping out of
sight in the mud, they seek for insects, molluscs, small fish, &c. If
any prey passes within their reach, they dart forward, like a spring,
a very singular arm, which represents the under lip. It is a sort of
animated mask, armed with strong jagged pincers and supported by
strong joints, the which, taken together, is equal to the length of
the body itself. This mask acts at the same time as a lip and an arm;
it seizes the prey on its passage, and conveys it to the mouth. "When
any aquatic insect approaches them at a time when they are in a humour
for eating," says Charles de Geer, "they shoot the mask forward very
suddenly and like a flash of lightning, and seize the insect between
their two pincers; then, drawing back the mask, they bring the prey up
to their mandibles, and begin to eat it. I have remarked that they do
not spare those of their own kind, but that they eat each other up
when they can, and I have also seen them devouring very small fish
which I put by them. It is very difficult for other insects to avoid
their blows, because, walking along generally in the water very
gently, and, as it were, with measured steps--almost in the same way a
cat does on the look-out for birds--they suddenly dart forward their
mask and seize their prey instantaneously."[118] Fig. 394 represents,
to the left, the larva of the dragon-fly, with the instrument of
attack which we have called a "mask," and which it is making use of
for seizing a small insect; on the right, the adult dragon-fly coming
out of the nymph.
[118] Charles de Geer, "Mémoires pour servir à l'Histoire des
Insectes," tome ii., 2e partie, p. 674.
[Illustration: Fig. 394.--Larva of the _Libellula_, and the perfect
insect emerging.]
[Illustration: Fig. 395.--Libellula depressa, the Common Dragon-Fly.]
The respiration of these larvæ is very singular. Their abdomen is
terminated by appendages, which they open to allow the water to
penetrate into the digestive tube, the sides of which are furnished
with gills communicating with the tracheæ. The water, deprived of
oxygen, is then thrown out, and the larva advances thus in the water
by the recoil. It has no tufts of external lateral gills, which in the
case of the _Ephemeræ_ do the duty of fins. The pupa already presents
stumps of wings. To effect its metamorphosis it drags itself out of
the water, where it has lived for nearly a year, climbs slowly to some
neighbouring plant, and hangs itself there. Very soon the sun dries
and hardens its skin, which all of a sudden becomes crisp, and cracks.
The dragon-fly then sets free its head and its thorax, and its legs;
its wings, still soft and wanting in vigour, gain strength by coming
in contact with the air, and, after a few hours, they have attained
their full development. Immediately the insect abandons, like a
worn-out suit, the dull slimy skin which had covered it so long, and
which still preserves its shape (Fig. 394), and dashes off in quest of
prey.
The _Libellulas_ are common all over the world. Their type is the
_Libellula depressa_ (Fig. 395), very common in Europe. The male is
brown, with the abdomen blue underneath; the female, of a sort of
olive-yellow, bordered by yellow on the sides. Both have the abdomen
broad and flattened.
The _Æshna_, with a cylindrical abdomen, attains to the length of two
and a half inches. Its flight is more rapid than that of the swallow.
The _Calepteryx_ flies more slowly. The male is of a metallic blue,
its diaphanous wings are traversed by a band of greenish blue; the
female, of a bronzed green, has wings of a metallic green, with a
yellowish mark on the edge. These insects rest on reeds, retaining
their wings in a vertical position.
[Illustration: Fig. 396.--Male Raphidia.]
[Illustration: Fig. 397.--Larva of a Raphidia.]
[Illustration: Fig. 398.--Pupa of a Raphidia.]
[Illustration: Fig. 399.--Mantispa pagana.]
The _Agrions_, which are of the same family, have the body white,
brown, or green, and the eyes very prominent. They are more slim and
graceful than the _Libellulas_, properly so called; their larva are
very elongated.
In the spring, one meets in the woods with insects having large heads
and elongated thoraces. The females have a long auger, with which to
deposit their eggs under the bark of trees, where their larvæ, which
feed on insects, and twist themselves about like small serpents, live.
The pupæ are also very active; they resemble the adults very much, and
have the wings laid against the body. These insects, which are met
with everywhere, but always in small numbers, are the _Raphidias_,
which we see represented (Figs. 396, 397, 398) in the state of larva,
pupa, and adult, and the _Mantispas_ (Fig. 399), one species of which
is common in the south of Europe.
[Illustration: Fig. 400.--Semblis lutarius, imago, pupa, and larva.]
M. Blanchard classes in the same tribe the genus _Semblis_, whose
larvæ are aquatic, with scaly heads, provided with eyes, and with
curved mandibles and short antennæ. The larvæ and the pupæ breathe,
like those of the _Ephemeræ_, by articulated external processes, or
gills, analogous to those of fishes. Nevertheless the pupæ live on
land, not in water. They hide themselves in the earth at the foot of
trees, and the adult issues forth at the end of a fortnight, leaving
its pupa skin behind. It lives but a few days. The female lays her
eggs on reeds, stones, &c. Fig. 400 represents the Mud _Semblis_ in
its three states.
[Illustration: Fig. 401.--Ant-lion (_Myrmeleo formicarius_).]
We now come to those Neuroptera which undergo complete metamorphoses.
They are the Myrmeleonidæ, of which the Ant-lion (_Myrmeleo_) is the
most prominent type, and the _Phryganidæ_, or Caddis Flies.
The larvæ of the Ant-lions live on the land, and are carnivorous. When
about to undergo their transformation into pupæ, they spin for
themselves a silky cocoon. The larvæ of the _Phryganeas_, on the
contrary, live in the water. They surround themselves with a sort of
protecting case, composed of a silky shell and incrustations of all
sorts. The pupæ, as well as the larvæ of these insects, breathe by
means of gills.
[Illustration: Fig. 402.--Ant-lion's funnel.]
[Illustration: Fig. 403.--Larva, cocoon, and pupa of the Ant-lion.]
The Ant-lion (_Myrmeleo formicarius_, Fig. 401) is found in the
environs of Paris. It is an elegant insect, resembling the dragon-fly,
but is distinguished from it by its antennæ. Its larva is of a rosy,
rather dirty grey, with little tufts of blackish hair on its very
voluminous abdomen. Its legs are rather long and slender; the two
anterior pair of legs are directed forwards, whilst the hind legs are
fixed against the body, and only permit the animal to walk backwards.
These larvæ are met with in great abundance in sandy places very much
exposed to the heat of the sun. There they construct for themselves a
sort of funnel in the sand (Fig. 402), by describing, backwards, the
turns of a spiral whose diameter gradually diminishes. Their strong
square head serves them as a spade with which to throw the sand far
away: they then hide themselves at the bottom of the hole, their head
alone being out, and wait with patience for some insect to come near.
Scarcely has the ant-lion perceived its victim on the borders of its
funnel, when it throws at it a shower of dust to alarm it, and make it
fall to the bottom of the precipice, which does not fail to happen.
Then it seizes it with its sharp mandibles, and sucks its blood;
after which it throws its empty skin out of the hole and resumes the
look-out. Ants especially become its prey, whence its name of
Ant-lion. Towards the month of July, the larvæ make themselves a
spherical cocoon, mixed with grains of sand, in which they are
transformed into pupæ which are hatched towards the end of August. The
perfect ant-lions diffuse an odour of roses; their flight, which is
weak, distinguishes them from the dragon-flies. We meet in the south
of France with a very beautiful species of Ant-lion, the _Myrmeleo
libelluloides_ (Fig. 404); its larva can move forwards, and does not
dig itself a funnel.
[Illustration: Fig. 404.--Myrmeleo libelluloides.]
[Illustration: Fig. 405.--Larva of Myrmeleo libelluloides.]
[Illustration: Fig. 406.--Larva of Ascalaphus.]
[Illustration: Fig. 407.--Ascalaphus meridionalis.]
The genus _Ascalaphus_ (Fig. 407) is remarkable for the long clubbed
antennæ of its members, and for their rapid flight. They like the sun,
and live especially in hot countries; however, one meets with the
_Ascalaphus_, in the month of July, near Paris, on the dry declivities
of Lardy and of Poquency. Their larvæ (Fig. 406) have mandibles
adapted for suction. They watch for insects under heaps of stones, and
spring upon their prey.
The first states of the _Nemoptera_[119] (Fig. 408) are as yet little
known. They are insects with wings spotted with yellow and black, the
lower ones almost linear, and are met with in southern countries, and
but very rarely in the south of France.
[119] From [Greek: nêma], a thread, and [Greek: pteron], a wing.
The _Hemerobii_, to which are given by the French the name of
_Demoiselles terrestres_, or Land Dragon-Flies, are very small
delicate insects, of an apple-green colour, with golden red eyes.
These insects leave on the fingers, when seized, an offensive odour.
Réaumur calls them _Lions des pucerons_ (Plant-Lice Lions), because
their larvæ, which resembles the larvæ of the ant-lions, and which
live on plants, feed on plant-lice. They attack also caterpillars.
Their mandibles are provided with a canal for suction, like those of
the foregoing species.
[Illustration: Fig. 408.--Nemoptera Coa.]
[Illustration: Fig. 409.--Osmylus maculatus.]
The insects of the genus _Osmylus_ (Fig. 409) are rather rare; but may
be found in the shrubs which border ponds. They also belong to the
_Hemerobidæ_. Their larvæ live in wet ground.
[Illustration: Fig. 410.--Panorpa, male and female.]
The _Panorpatæ_ constitute a singular little family, having a peculiar
shaped head, which is prolonged to a sort of long and slender beak.
Aristotle called them Scorpion Flies, and thought they were winged
scorpions. The _Panorpas_, properly so called (Fig. 410), are found on
hedges and plants during the summer. They have slim bodies spotted
with yellow and black, and four straight wings, also spotted with
black. In the males the abdomen terminates in a pair of pincers (Fig.
411), which rather remind one of the tail of a scorpion, and which are
destined to seize their prey, which they kill by piercing with their
beak. The female lays her eggs in the ground (Fig. 412). In a week the
larva makes its appearance; it is a month in developing, it then
buries itself still deeper in the earth, and changes into a pupa,
which, after a fortnight, comes again into the light in the form of a
perfect insect. There are two other genera of _Panorpatæ_, of which
_Bittacus tipularis_ (Fig. 413), resembling a large gnat, furnished
with four wings, and _Boreus hyemalis_ (Fig. 414), of a brilliant
black, met with in Sweden and in the elevated parts of the Alps,
jumping about on the snow in considerable troops--are representatives.
The latter has been found in England.
[Illustration: Fig. 411.--Pincer of male Panorpa.]
[Illustration: Fig. 412.--Female Panorpa laying.]
[Illustration: Fig. 413.--Bittacus tipularis.]
[Illustration: Fig. 414.--Boreus hyemalis (magnified and natural size).]
[Illustration: Fig. 415.--Larva of Phryganea rhombica.]
[Illustration: Fig. 416.--Phryganea rhombica, in repose.]
[Illustration: Fig. 417.--Phryganea rhombica.]
The _Phryganidæ_, or Caddis Flies, are known by their larvæ, of which
anglers make great use. Réaumur classed them as aquatic moths. The
soft and delicate body of the larvæ is protected by a case, to which
they cling by two hooks, placed at the extremity of their abdomen.
They are called by different names in allusion to their habits; as,
for instance, case worms, from their living in a case covered with
little bits of wood or sand, which they draw after them as they go.
Their scientific name, _Phryganea_, signifies _fagot_.[120] The
_Phryganeæ_, in the adult state, very much resemble moths. They
approach them in having rudimentary mouths, and wings without
articulations, but furnished with small hairs, analogous to the scales
of Lepidoptera. They may be said to form a sort of connection between
the Lepidoptera and Neuroptera. They have been called _Mouches
papilionacées_, or Papilionaceous Flies. The eggs laid by the female
_Phryganea_ are enclosed in gelatinous capsules, which swell in the
water and attach themselves to stones, &c. The larva has the
appearance of a little worm without feet. It is soon hatched, and
resembles at first a little black line, and may be easily reared in an
aquarium. The operation of making the silky case which it draws after
it, and which protects its abdomen, may then be observed. When it is
disturbed, it retreats entirely within its case. The interior is
smooth, and lined with mud; on the exterior it is fortified with
stones, &c.
[120] From [Greek: phryganion], a stick.
[Illustration: Fig. 418. Regular cases of a Phryganea.]
The _Phryganea rhombica_ (Figs. 415, 416, 417) furnishes its case with
bits of wood or grass, arranged as shown in Fig. 418. Some species
arrange these bits of wood and glass in spiral, others in parallel
series. The _Phryganea flavicornis_ covers its dwelling with little
shells. "These kinds of dress," says Réaumur, "are very pretty, but
they are also excessively singular. A savage who, instead of being
covered with furs, should be covered with musk rats, moles, or other
entire animals, would have on an extraordinary costume; this is in
some sort the case with our larvæ." Other _Phryganeæ_ employ for
constructing the case which serves them as a dwelling sand and small
pebbles; each species always employing the same materials, unless they
are entirely deprived of these and obliged to employ others. These
cases protect the larvæ against the voracity of their enemies. The
larvæ have a scaly head; and the three first rings of their body are
harder than the rest. They live in water, and breathe by means of
branchious sacs, arranged on the abdomen in soft and flexible tufts.
They eat everything that is presented to them: leaves, and even
insects and the larvæ of their own kind. The pupæ are motionless. They
stay about a fortnight in their case, the orifice of which is closed
by gratings of silk, then break through the gratings, and leave their
prison. In this state (Fig. 419) they swim on the water until they
meet with an object to which they can attach themselves, and so get
out. Then they swell till they crack their skin over the back, and the
perfect insect emerges.
The _Phryganea pilosa_ (Fig. 420) is of a yellowish grey, with hairy
wings, little adapted for flying. These insects do not eat, and never
leave the neighbourhood of the water. During the day they rest on
flowers, on walls, or on the trunks of trees, their wings folded back,
and their antennæ together. In the evening they fly in dense swarms
over streams and ponds. They are attracted by light, as are many
nocturnal insects; and are sometimes found in great numbers on the
lamps on the quays in Paris.
[Illustration: Fig. 419.--Pupa of Phryganea pilosa, magnified.]
[Illustration: Fig. 420.--Phryganea pilosa.]
The _Hydropsyches_ (Fig. 421) and _Rhyacophili_ (Fig. 422) are small
insects which resemble the _Phryganeæ_ very closely. Their larvæ have,
for the purposes of respiration, some gills, others retractile tubes.
They construct for themselves fixed places of shelter, more or less
imperfect, at the bottom of the water, and against large stones,
which they leave occasionally for a few moments. Sometimes these
cases contain several larvæ. Fig. 421 represents the various states of
a _Hydropsyche_; the larva is seen on the left, the pupa on the right,
the winged insect in the middle. Two of the insect's tents, or places
of shelter, are represented below. Fig. 422 shows the different states
of _Rhyacophilus vulgatus_, larva, cocoon, pupa, and imago. The genus
_Rhyacophilus_ has this peculiarity, that the larva spins itself a
cocoon in the interior of its dwelling before changing into a pupa.
[Illustration: Fig. 421.--Hydropsyche (Phryganea) atomaria, larva,
pupa, imago, and larva-case.]
[Illustration: Fig. 422.--Rhyacophilus vulgatus, larva, pupa, cocoon,
and imago (male).]