True Tales of the Insects

P)Ut of all the strange characteristics of the Phasmidse, none is more strange than the eggs they lay. Certainly they are of a most remarkable nature, and very different from insects' eggs in general (see Fig. 13). Hardly any one sees them without observing their extreme resemblance to seeds. It has been suoraested that this is for the purpose of deceiving Ichneumons; but if it be so, the imposition may fail of effect, since the eggs are known to be actually destroyed by Ichneumons. Those oi Dia-pheromerafemorata are flattened and elHptical, resembling beans, with an oblique yellow punctured lid or cap at one end; they are brown, with one side— which shows an

with yellow. In Bacferia cormitaelongated pit—banded they greatly resemble leguminous seeds; the little

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Fig. 13.—Eggs of diFferent walking-sticks.

operculum at the end is distinct on a smooth edge which it exactly fits, the rest of the surface being variously impressed. In some species the cap becomes a sort of knob, and carvings of different desigfns are seen on the sides of the ^g'g itself, particularly about the part that presents the sunken pit. These eggs are deposited in no careful way, not secured to any object, but, it is worthy of remark, are shed like seeds, being dropped at random loosely on the ground; for the mother, unlike most orthopterous insects, makes no provision for their safety. The noise caused by the dropping of the eggs Q){ Diaphcromera fenioi^ata from the plants on which the insects are feeding to the grround, migfht be mistaken for the pattering of rain. Thus unprotected, the eggs of this species sometimes lie till the second year before

hatchingr. Yet in a certain way the ^^^ is protected, for each ^c?& ^^ really a capsule or sac containing an ^'g%,

and the lid or cap with which it is provided, already referred to, is pushed off by the embryo when about to hatch. Although the present state of investigation does not admit of speaking definitely on the point, the generally received opinion is that the egg-capsules are formed in the egg-tubes, only one Qgg being formed at a time in a tube. This capsule has induced some investigators to believe that the egg contained therein is really a pupa; that all the larval stages are undergone in the egg, and that the insect after emergence should be looked upon as an active pupa that takes food. Comparatively few eggs are produced, from twelve to twenty or thirty being the usual number, but more have been noticed in the case of Diapheromera. Laying takes place in the autumn, emergence between the months of May and August. Perhaps of all the eggs, those of the walking leaves are the most curious, and their resemblance to seeds is especially striking. At different times specimens of Phyllium have been introduced into Europe, and raised from the Qgg, affording entomologists the opportunity of studying them. The egg-capsules of Phyllium scythe are of the size of a fair-sized pea, though not of that shape. " If," says Murray, " the edges of the seed of Mirabilis ialapa were rubbed off, the seed might be mistaken for the egg!' What may be called the back and sides are

deeply ridged, and the front is flat, with a slender fusiform plate on the middle; in other words, all the ribs are about equi-distant, except two, which are wider apart, and the space between them flatter, so that when the egg falls it rolls over until it comes to this side, and so lies. All except the front is pierced, as it were, with holes, giving the porous aspect of the bark of trees. At the top a tiny conical lid, roughly resembling a Phrygian cap, fits tightly to the mouth. On removing the lid a beautiful white chamber is espied, smooth like porcelain.

The resemblance to seeds displayed by these eggs extends not alone to appearance and to shedding, but even the minute structure of the capsule bears a close resemblance to vegetable tissue. It has been examined by several entomologists; and Henneguy, who enters into some detail in his account of the eggs of Phyllium crurifolium, says, “Almost every botanist, on examining for the first time a section of this capsule, would declare that he is looking at a vegetable preparation.”

The Scramble out of the Egg; and After.

We will suppose the young phasma in the egg to have acquired its six legs and to be ready to hatch. In the egg it is packed away in a truly marvellous manner. In

the full-grown insect, we know, the three parts of the thorax, each of which carries one pair of legs, are of very unequal length, the first pair of legs being borne by the wonderfully short prothorax, as compared with which the meso- and meta-thorax are remarkably elongated. But in the &gg this great difference of length of the three divisions does not exist, so that the legs are not very far apart, and pack away closely. But the instant the creature has fairly escaped from its prison-house, the eeS', the usual difference in the length of the several thoracic segments is attained; much expansion of the body comes about during the withdrawal out of the ^gg, so that it is hard to understand how it was contained therein; it looks, indeed, like a juggler's trick.

Of the subsequent development of the insects, practically we know very little. But the observations made indicate great differences in the length of time occupied by it, and in the number of moults. Some species are stated to moult many times; Diapheromera fcmorata is said to reach the perfect stage in six weeks, and to moult only twice: while according to Murray, who had some specimens under his observation during the whole course of their development, Phyllium takes no less than fifteen or sixteen months to complete its growth, and during that period undergoes only three moults, the first of which does not happen until the tenth month after hatching; it is interesting to learn that the first moult observed

took place when the young- PhyUium had attained the length of an inch. It may be mentioned that nothing is more difficult than to watch all the successive moults of an insect of the orthopterous order, since it is their the habit has been remarked in Phylliumhabit—and to devour their skin almost as soon as it is shed; all trace of the occurrence will be over in the space, say, of half an hour. The day previous to the transformation the young Phyllium showed signs of great agitation, and the body was subject to repeated shakings, eventually ending in the rupture of the skin. At each change of skin there is an immediate increase in size, similar to the enlargement occurring on emergence from the Qg%, each limb becoming about a fourth larger and longer than the corresponding portion of the envelope out of which it has that moment been drawn. In Phyllium the abdomen especially enlarges after each moult. When freshly hatched it is of a reddish yellow, like a half-dried leaf; for though the colour varies at different periods of its life, it always more or less resembles a leaf. After it has settled to eat the leaves it speedily becomes a beautiful bright green. This colour, as the season advances, gets mixed with yellow, almost passing to the tint feuille-mort, suggesting autumnal foliage, or at least a decaying leaf, agreeable to the very tints which the leaves go through themselves.

In no group of insects as a whole is it more difficult to distinguish the young and the adult states. Among the winged species it is not always possible to distinguish on a young form whether it will, or will not, in course of time, receive the organs of flight. According to Murray, the wings in Phyllium disclose themselves in the period of youth by slight swellings on the meso- and meta-thorax, but it is very doubtful if this character is always well indicated. In Phyllium the organs remain of very small size till the third moult, which suddenly liberates them in their full development; they are drawn out of little cases about a quarter of an inch long, and a few brief moments suffice for them to attain their perfect size of about two and a half inches; half an hour after the last moult the insect is fit for flight. The same may be said of their long antennce, which are twent}- four jointed as possessed by the adult males, contrary to the females, which have them much shorter, consisting of but nine joints. But these organs remain rudimentary in the two sexes during the young period: it is only in the last moult that they acquire among males their normal length, suddenly shooting out with twenty-four joints. Among the subapterous insects there are species which keep in the adult state the wings in the immature form, analogous to that of the young insects. We cannot, therefore, from the appearance the rudimentary wings assume deduce any positive character, that can help us

to distinguish, in every case, the larvce from the adults. We can only affirm that, as often as the elytrum or the wing is separate and articulated, the individual is an adult. In a great number of the apterous species it is often quite impossible to distinguish the larvce and nymphs from the perfect insects.

CHAPTER IV.

WALKING-STICKS AND WALKING-LEAVES (pHASMID/E)—

continued.

Fig. 14. Acrophylla titan.

MaTvellons Imitative Resemblance. We come now to speak of that wonderful characteristic of the Phasmidse, which renders them amongst the most singular of known insects, which is most likely to attract the stranger, from which they have been given their imitative resemblance to vegetative objects.names—their

Fig 15.—A Stick Insect (P/ianocks curvipes), from St. Vincent.

The perfection of this resemblance in certain cases one cannot conceive; it is marvellous; no insects display this kind of imitation so perfectly. Those with slender body, long and cylindrical, so as to resemble sticks, might be mistaken for the latter with all the minutiae of knots and branches, formed by the insects' legs, which may be stuck out rigidly and unsym metrically. Dr. Wallace, the naturalist, familiar with them in tropical forests, describes them in the Moluccas " hanging on shrubs that line the forest paths; and they resemble sticks so exactly in colour, in the small rugosities of the bark, in the knots and small branches imitated by the joints of the legs, which are either pressed close to the body or stuck out at random, that it is absolutely impossible by the eye alone to distinguish the real dead twigs which fall down from the trees overhead from the living insects." And he adds that he has " often looked at them 'in doubt, and has been obliged to use the sense of touch to determine the point." Some are small and slender, like the daintiest of straws or twigs; their body sometimes an inch and a half, sometimes barely an inch long, the legs like threads; others are of a much larger and stouter kind. The larger wingless sticks (see Fig. 15) are often eight inches to a foot long. Many of these are hardly thicker than a knitting-needle. In Mexico, for instance, Phanocles is about eleven inches long in all, and exhibits the odd knitting-needle effect, enlarging