True Tales of the Insects

Next to the enlarged front [L^p/ocola gracilinia) with atrophied wings. legs, with their adaptation to a particular end, the most striking lineament of these insects is the long prothorax, it being the longest

segment of the body; among slender types (see Fig. 4) the lengthening may become marvellously pronounced. This piece is, in fact, elongated into a narrow neck, rather dilated in front, above the insertion of the anterior legs, to give added strength to their articulation (see Fig. 5), leaving a long, flat, narrow space on the under side behind these legs; the remainder of the thorax is short, and hid by the wings and wing-covers in the position of rest.

This remarkable development shows the importance of this part of the body, the movements of which play no mean role in the pursuit of prey. Its articulation with the meso-thorax is very supple; it is raised obliquely, it may be turned to either side with the greatest liberty, the body meanwhile being supported solely by the two posterior pairs of legs. The lengthening of the prothorax, we may believe, has been promoted by the habitual projection in front of the rapacious legs, and to their presence towards the end of the long elevated neck is in part due the mobility of its mesothoracic

articulation. Not that the legs and thorax are the only parts arranged with reference to the wants of the insects. Their whole org-anization, as with all animals that orive chase to living prey, is superior, and is in direct conformity with a carnivorous life, which demands at the same time perfected senses, and great vigour and suppleness. The head, instead of being bound in the

prothorax, enjoys great mobility, and may be turned in every way, even so as to bring the mouth obHquely upwards. Its customary position is vertical, or bent up against the prothorax, the mouth applied against the neck. It is triantjular—sometimes rounded or lone especially with the great bulged eyes, which in general occupy the su- perior angles, to enable the insects to see in many direc- t i o n s. The size of the visual organs, no less than their position, denotes a well- developed sense; and simple eyes, or ocelli, are never wantine- The body, though sometimes su f f i- ''PJi ciently thickset, is usually Fig. 5.—Head ami jirolhorax long and nar-religiosa, Mantis withrow. of A s one insertion lees. of anterior would expect amono- hunting insects, the organs of flight are often amply developed, and powerful enough to cover considerable distances. The upper pair, or elytra as they are called, are as long as the abdomen, or sometimes extend in both sexes beyond the extremity of that piece, over which they are carried horizontally when closed, one greatly overlapping the other. Compared with the hinder pair, they are at least as long as they, with a few exceptions,

but they never become enormously abbreviated, and always serve as sheaths or covers to the wings. They are coriaceous or membranous, those of the males constantly longer and narrower than in the females, and always more transparent. The wings are large, and, being well protected in rest, remain membranous, though they often extend a little beyond the elytra; the exposed tip tends to become indurated.

Atrophy of the Wings.

There exist frequent cases, however, where the organs are atrophied more or less, especially among the females. The abbreviation is pushed the farthest in mantidae of stick-like form, for a body excessively lank and long almost precludes the power of flight, and condemns the species which possess it to a pedestrian life (see Fig. 4), To these insects flight would be possible only with wings of great size, and the narrowness of the body does not permit the muscles to enlarge sufficiently to move such organs easily; whereas the bigger mantidse of this shape have wings always more or less undeveloped.

But the females seem never entirely apterous; on the thorax always persists some trace of the organs of flight. Thus among certain species (Coptopteryx) where the elytra alone become developed to a rudimentary

State, even in these rare instances the wings are not ahogether obHterated, but are invariably indicated under the form of striate lobes, as in the nymphs.

In addition to the previously mentioned characters, the males have longer antennae than the females, they have larger eyes, a narrower prothorax, and longer and more slender raptorial legs; but more decided sexual differences occur.

II. CHAPTER

niE devil's riding-horse (mantid/e)— continued.

-V A..1.,

and surrounds and shelters the eofcrs. The whole mass terminates in a sort of neck that sticks to the stem, or is directed upwards, lending the capsule the appearance of a seed or fruit, for which indeed it has been frequently mistaken. These capsules, or oothecce, as they are technically called, vary with the species (see Fig. 6). Many are most fragile, some of much beauty, and their internal structure is of marvellous regularity; it is no exaggeration to say that, at the first glance, one might easily take them to be organized bodies. If generally the parent dies after laying, this is not always the case, for a mantis has been known to fashion successively four capsules, and even to establish six different ones, at intervals of seven or eight days; but in Europe the parent invariably succumbs before the arrival of cold weather. Seeing, then, that the young brood produced in autumn remain in the o.'g'g state until the followino^ summer, the mantidse disappear entirely during about six months, for there is only one annual laying. But in warm climates, in all probability, the life of these insects does not suffer an interruption equally great, and already, in southern parts of Europe, we find indication of the fact in the genus Empusa, which hibernate in the state of larva, and transform in the subsequent spring.

An examination of the ellipsoid capsule of the the way, it attainscommon mantis, Mantis religiosa—by c

i8 TRUE TALES OF THE INSECTS.

is well wortha leneth of more than three centimetres-making (see Fig. 7). The gummy mass voided by the insect has been spread out, we see, into a succession of layers, fitting lightly by their curvature, rounded and equalized on the surface in the form of the ovoid cap, the layers being of insignificant thickness. A transverse cutting of the capsule shows that each layer is divided into three parts; a median chamber or sac, like a flat bottle, open at the top, containing, towards the bottom, the eggs, which are narrow, longish, yellow in colour, and to the number of eight to ten, resting by their large end, and adhering to the floor of the mass; and all ranged on the same plan, somewhat fan-wise, diverging towards the floor, and in most symmetrical order, one half on either side, with or without a central ^tgg; moreover, each is enveloped in a gummy pellicle. The two walls of this flat bottle or cell which contains the eggs are very tough and chitinous, and each partition narrows above the space enclosing the eggs, and terminates in a neck, by an arched lamina or scale, imbricating with the lamina of the partition above, in the direction of the small end of the mass. Together these laminae constitute a scaly band on the median line of the convex upper side of the capsule, dividing the surface into two symmetrical parts. By the terminal scale of each partition imbricating with the scale of the partition following, the cell with the eggs placed between the two partitions is closed, that is to

say, a sort of elastic operculum is formed, which, after hatching, the larva: have to raise in effecting their egress through the neck. Laterally to the important compartment with the eggs, on either side are envelopes, formed of a foamy substance, chitinous, but very light, made up also of arched cells, and disposed by successive layers, corresponding to the succession of the central chambers. To these they must be regarded as mere protective casings, since they contain no eggs. It is also in the light of protection that one must look upon the layers of the two extremities of the capsule. They do not contain eggs, and consequently present no horny central cell, but are composed solely of cellular tissue, analogous to that of the two lateral zones of the other layers; they simply afford additional strength to the ends of the structure. The highest and lowest cells that envelop eggs are smaller than the rest, and possess only two, four, or six of these little objects, for whose well-being alone they were established. The capsule is at first soft and whitish, but soon darkens, and becomes firm, parchment-like, or very

resistant, and tears only with difficulty, and is impermeable to water. It may be plunged into liquid without the eggs being injured, so admirable the closure of the opercular scales one upon the other.

It is not easy to understand how the mantis, simply by the act of laying, contrives to form a structure so wonderfully regular, and so complicated as this capsule; it would be a clever bit of work were it built by the mouth and feet, but fashioned as it is, it appears a conjuror's trick. The insect begins to establish the edifice at the large end; and whilst the viscous matter flows, the abdomen is caused to assume a circular, undulatory motion, ceaselessly working up the gummy mass, and arranging it in the successive concave layers. It must be supposed that for each layer she at first dis-charges the eggs clothed, as it were, in gummy stuff, which in drying hardens, and becomes the central horny sac, and then to right and left she deposits a viscid fluid less strong, known to us eventually in its solidified state in the shape of the lateral foamy cells.

Curiously enough, the eggs at the small end of the ootheca hatch first, although these were the last deposited.

The European Ameles, small mantidae which likewise inhabit the Mediterranean basin, have prismatic capsules, about two centimetres long, composed of a most neat series of triangular cells, each enclosing six or seven eggs, almost destitute of lateral cellular tissue.

In spite of all the mother's care, chalcidideous parasites infest her eggs to some extent. Several species have been obtained from the eggs of mantidse of Mauritius and Brazil, and those of Mantis religiosa, in Cephalonia, are known to be attacked. It is probable that the parasite seizes her opportunity to start the career of her progeny before the glutinous covering has acquired its final consistency.

Development of the Yonng.

Step by step, we may study the development of be taken as the type ofMantis religiosa—which may the mantidae— and see these eggs, on the whole securely housed, change to larva, to pupa, and at last to imago. To the lot of the mature insect short life falls; in turn it propagates its kind, and that done, in submission to the winter's cold, it dies. The eggs do not hatch till June, and only after a lapse of nearly three months the mantis arrives at the perfect state.