Chapter IV: Lepidoptera (5)

That is what our naturalist saw when he placed larvæ 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 that to 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 we 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 in a piece on each side if the shape of the tube seemed to require it. This is also exactly what our larvæ 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."

The wools of our stuffs furnish the moths not only with clothing, but also with food. Their excrements are little grains, which are the same colour as the wool they have eaten.

When they are full grown, and the time approaches for their metamorphosis, the larvæ abandon their food, and establish themselves in the angles of walls. They creep up to the ceilings and suspend themselves to them by one extremity of their tube. The two ends of the tube are now closed by a silken tissue (Fig. 296). The larva thus enclosed very soon changes its form; it becomes a chrysalis; then at the end of about three weeks it is set free as a moth.

The Fur or Skin Moth works like the carpet moth: it makes itself a case of the same form, and constructs it in the same manner. Only in this case its covering is made of a sort of felt resembling that of which our hats are made.

While the Carpet Moth only detaches from the various stuffs the wool it requires for clothing and nourishment, the Fur Moth causes much more considerable and more rapid damage. It cuts off all the hairs which are in its way right down to the skin; it seems as if it took a delight in cutting them off. That which is necessary for its wants is nothing in comparison to the great quantity of hair one sees fall off a skin on which it has established itself, when it is shaken. As it advances it cuts more thoroughly than a razor could all the hairs which are in its way.

The Hair Moth (Fig. 297) shows itself in great numbers in the perfect state, from the end of April till the beginning of June. They appear again in September, and generally stay behind cabinets and other pieces of furniture.

The caterpillar, which is cylindrical, white, destitute of hair, and striped with brown, lives principally in the hair with which furniture is stuffed, and sometimes in hair mattresses. When it has reached its full size, it abandons its abode, pierces through the stuff which covers the hair, and constructs for itself with this stuff a case of silk, open only towards the end where the head is. At the beginning of April it shuts its case, and changes itself into a chrysalis.

We can only here mention some of the phytophagous species, as the Cherry-tree Moth (_Tinea cerasiella_), the Hawthorn Moth (_Tinea cratægella_), the Burdock Moth (_Tinea lapella_), and the Rustic Moth (_Tinea rusticella_).

The caterpillars of the _OEcophoræ_ resemble whitish worms. They attack the leaves, the blossoms, the bark, and certain parts of the fruit of trees. Some of these hollow out for themselves galleries in eating the fleshy part; others also make galleries, but only in the cuticle of the tree, or in the tenderest part of its bark. Some, again, shut themselves up in one or many leaves rolled like a trumpet, while others keep at the summits of plants, whose leaves they bind together in a parcel with threads. And, lastly, some devour the stones of fruits, such as that of the olive.

The moths of these caterpillars are very small, and generally of brilliant metallic colours, they are to be found in the woods, and still more in the orchards, from the beginning of June till the month of September.

The _OEcophoræ_ are very slim and elegantly formed. Their anterior wings, which are very narrow, are often ornamented with silvery longitudinal lines, the posterior wings exactly resembling two feathers.

The caterpillars live and metamorphose themselves in portable cases, which they manufacture from the membranous portions of leaves, whose flesh alone they eat. These cases are generally of a brown colour, resembling a dead leaf. They are attached perpendicularly under the leaves of many trees, but often under those of fruit trees.

Certain species of _OEcophoræ_ have cases partly covered with loose pieces only slightly attached, formed of portions of leaves, and arranged in such a way that Réaumur compares them to the furbelows which ladies used formerly to attach to the bottom of their dresses.