The Insect World: Being a Popular Account of the Orders of Insects

Fig. 289.— Chrysalis of the Vine Pyralis. according to the different places in which it occurs, vine worm, summer worm, vintage worm, shell. In the south of France it is called, in the patois of Languedoc, habota. Almost immediately aftei they leave the eggs, the little caterpillars hide themselves in the fissures of the vine stocks or the props which support them. They spin a small cocoon of a greyish silk, in which they remain curled up ill the month of May. From the moment the leaves begin tc

LEPIDOPTERA.

Pig. 290.— The Vine Pyralis in its three states, i. Leaf with batches of eggs laid upon it. 2. Batches of recently laid eggs. 3. Eggs in which caterpillars can be perceived. 4. Batch of eggs from which the caterpillars have already emerged. 5. Small caterpillars hangmg by threads. 6. Leaf with the chrysalis. 7. Caterpillar. 8. Moth.

develop they throw out threads here and there, entangHng all the young shoots of the vine, which gives a desolate appearance to the

vineyards. The leaves of the vine are their favourite food, but they attack the seeds of the grape also. As they increase in size every day, the damage they do goes on increasing, and has not reached the inaximum of intensity till the moment when the caterpillars are about to change into chrysalides. They are then three-quarters of an inch long and of a yellowish green colour.

From the 20th of June to the loth of July they seek shelter in the dry and interlaced leaves which have already served them for places of refuge and partly also for food, or else they make themselves afresh nest.

At the end of two or three days, the caterpillar has become a chrysalis (Fig. 289), which in a short time assumes a brown colour. Shut up in the interior of the cocoon which the caterpillar had spun before undergoing its metamorphosis, it changes into a moth at the end of from fourteen to sixteen days.

The best way to diminish the ravages of the pyralis is to pluck off the leaves which are laden with eggs, and burn them, or bury them in deep holes.

Fig. 290, which we devote to the conspicuous insect whose destructive history we have been here able to sketch only slightly, gives all the particulars relating to this dangerous guest of the vineyards. On a branch of the vine may be perceived the pyralis in the caterpillar state, the eggs which have been laid by the moths, the chrysalides, and perfect insects. The eggs are shown at two periods of their development. The Bee-hive or Wax Galleria is to be met with in all countries where bees are reared. The moth (Fig. 291) hides itself ^ ''^"^^ during the day round about the bee- Fig. 291.— Galleria cereiia. hivcs, and cndeavours to make its way into them after sunset. The caterpillar is of a dirty white, with brown warty spots, each surmounted by a fine hair. It lives on wax, twines its threads round the honeycomb, and very soon causes the larvae contained in it to perish. When it emerges from the ^%g^ which the female has laid in the honeycomb, the caterpillar makes for itself with the wax a round tube, in which it is safe against the stings of the bees. This tube, at first very small, is lengthened and enlarged as the caterpillar increases in size. It is generally from three to five inches in length. It is in

LEPIDOPTERA. 21 Qi

the interior of this that the caterpillar constructs itself a hard cocoon, resembling leather, and it changes into a brownish chrysalis.

A species of the genus Butalis, the Btitalis or Aliicita granella, is, in certain cantons of France, one of the greatest pests to agriculture. The caterpillar of the Tinea granella undergoes its metamorphosis in the interior of grains of barley and of wheat, which it devours without being perceived from without. The female lays her eggs on the grains of corn before they are ripe. From four to six days after, the eggs are hatched, and the young caterpillars are hardly as thick as a hair. Tine?graneiia. Each one takes possession of a grain of corn, and penetrates into it by an imperceptible opening. They eat the flower without injuring the teguments of the grain.

When it has attained its full size it spins itself a cocoon of white silk in the interior of the grain, which, after having been its lodging and its larder, becomes for some time its tomb. It has, however, taken care beforehand to make at the extremity of the grain a circular opening, through which the moth may come out when the grains have been threshed and stored up in the granary.

It is important to mention the Tineina, not because these little moths are beautiful — they are, on the contrary, very dingy — but because it is in this group that are found those insects which do the greatest damage to our crops. The moths of the genus Tinea are very small. Their wings, which are greyish or brownish, are generally marked with whitish and yellowish spots or lines. These are the little moths which, in our houses, burn themselves so frequently in the flames of the candles (Fig. 292).

Their caterpillars are small, voracious, and deserve, on account of the damage which they cause, to be compared to rats and mice. Furnished with powerful jaws, they destroy everything they find in their way, such as woollen stufls, hair, furs, feathers, grain, &c.

The Tineina are divisible into three groups: ist, the species hurtful to our stufls and furs; 2ndly, the species which destroy our corn crops; srdly, the phytophagous species, that is to say, those which feed on plants. In the first sub-division must be classed the Fur Moth, the Woollen Moth, and the Hair Moth.

The Woollen Moth is represented in the figure on next page. Its caterpillar has the form of a worm, and is of a glossy whiteness, with a few hairs thinly sprinkled over it and a grey line on its back. It is enclosed in a tube, or sheath, open at both ends, in the interior of

2So THE INSECT WORLD.

which is a sort of tissue of wool, sometimes bkie, sometimes green,

sometimes red, according to the colour of the stuft" to which the insect attaches itself and which it despoils. The exterior of this sheath is, on the contrary, formed of silk made by the insect itself, of a whitish colour. The caterpillars are hardly hatched before they begin to clothe themselves. Reaumur observed one of these worms during the operation

Fig. 293. The Woollen Moth of enlarging its case. To do this it put its head out of one of the extremities of its sheath, and {7'ifU'ti tapezelld). looked about eagerly, to the right and to the left, for those bits of wool which suited it best for weaving in. In

Fig. 294, we see two larvae occupied in eating a piece of cloth.

Fig, 294. — Larvae of the Woollen Moth {Tinea tapezclla).

" The larva changes its place continually and very quickly," says Reaumur. " If the threads of wool which are near it are not such as it desires, it draws sometimes more than half its body out of its case to go and look for better ones farther off. If it finds a bit that pleases, the head remains fixed for an instant; it then seizes the thread with the two mandibles which are below its head, tears the bit out after redoubled efforts, and immediately carries it to the end of the tube against which it attaches it. It repeats many times in succession a similar manoeuvre, sometimes coming partly out of its tube, and then

again re-entering it to fix against one of its sides a new piece of wool."

After having worked for about a minute at one end of its tube, it thinks of lengthening the other. It turns itself round in its tube with such quickness, that you would imagine it could not have had time to do so, and would think that its tail was formed in the same way as its head, and possessed the same address in choosing and tearing out the bits of wool. Furthermore, when the moth which is working at elongating its case does not find the threads or hairs of wool to its taste within reach of its head, it changes its place. Reaumur saw this insect walking, at some speed even, carrying with it its case. It walks on its six front legs (Fig. 295). With the middle and hind legs it clings to 1■njiiiyV'i) IJlWr^^f^ the interior of its case.. ^^^^^^^Swuf^jj^;.,^

At the same time that the larva " • • ' ^^^Bs^^J^^^»^_" becomes longer it becomes stouter. Very soon its garment will be too ^'g- 295-— Larva of a Tinea walking. narrow for it. Will it enlarge its old coat, or will it make itself a new one? Reaumur discovered that it preferred to widen its old coat.

That is what our naturalist saw when he placed larvae with blue cases, for instance, upon stuff of a red colour. The bands which extended in straight lines from one end of the case to the other, showed the part that had been added.

"From watching them at different times," says this admirable observer, " I find that the means which they employ is precisely thatto which we should have had recourse in a similar case. We know of no other way of widening a sheath, a case of any stuff that w^e find too narrow, than to split it right up and to let in a piece of the proper size between the parts which we have thus divided; we should let m a piece on each side if the shape of the tube seemed to require it. This is also exactly what our larvae do, with an extra, and which with them is a necessary, precaution, so as not to remain exposed while they are working at the enlargement of their garment. Instead of two pieces, which should each be as long as their case, they let in four, each of which is not longer than half the length of their case; and so they never split up more than half the length of the case at the same time, which has enough stuff left in it to keep it together while this opening is being filled up."