As the result of a more rapid desiccation on the ravaged surface, the leaf soon begins to curl of its own accord, curving into a gondola which is covered by a continuous awning stretched from end to end. The herbage is then exhausted. The flock abandons it and begins again elsewhere in the near neighbourhood.
After various temporary pastures of this kind, in November, when the cold weather is at hand, the caterpillars settle permanently at the end of a bough. Nibbled one by one on their upper surfaces, the leaves of the terminal bunch draw close to their neighbours, which, excoriated in their turn, do the same, until the whole forms a bundle, which looks as if it had been scorched, lashed together with magnificent [[154]]white silk. This is the winter habitation, whence the family, still very feeble, will not issue until the fine weather returns.
The assembling of this leafy framework is not due to any special industry on the caterpillars’ part; they do not stretch their threads from leaf to leaf and then, by pulling at these ropes, bring the various pieces of the structure into contact. It is merely the result of desiccation on the nibbled surfaces. Fixed cables, it is true, solidly bind together the leaves brought close to one another by the contraction due to their aridity; but they do not in any way play the part of a motive mechanism in the work of the assemblage.
No hauling-ropes are here, no capstans to move the timbers. The feeble creatures would be incapable of such effort. The thing happens of itself. Sometimes a floating thread, the plaything of the air, enlaces some adjacent leaf. This chance footbridge tempts the explorers, who hasten to strip the accidental prize; and, without other labour, yet one more leaf bends of its own accord and is added to the enclosure. For the most part, the house is built by eating; a lodging is procured by dint of banqueting. [[155]]
A comfortable house, tightly closed and well-caulked, proof against rain and snow. We, to guard ourselves against draughts, put sand-bags against the cracks of our doors and windows; the extravagant little Arbutus Caterpillar applies pipings of silk-velvet to his shutters. Things should be cosy inside, however damp the fog. In bad weather, the rain drips into my house. The leaf-dwelling knows nothing of such troubles, so true is it that animals often enjoy advantages which relegate human industry to the second rank.
In this shelter of silk and foliage, the worst three or four months of the year are passed in a state of complete abstinence. No outings; not a bite of food. In March, this torpor ceases; and the recluses, those starving bellies, shift their quarters.
The community now splits up into squads, which spread themselves anyhow over the adjacent verdure. This is the period of serious devastation. The caterpillars no longer confine themselves to nibbling one surface of the leaf; their keen appetites demand the whole of it, down to the stalk. And now, stage by stage, halt by halt, the arbutus is shorn bare.
The vagabonds do not return to their winter [[156]]dwelling, which has become too closely cramped. They reassemble in groups and weave, here, there and everywhere, shapeless tents, temporary huts, abandoned for others as the pasturage round about becomes exhausted. The denuded boughs, to all seeming ravaged by fire, take on the look of squalid drying-grounds hung with rags.
In June, having acquired their full growth, the caterpillars leave the arbutus-tree, descend to earth and spin themselves, amid the dead leaves, a niggardly cocoon, in which the insect’s hairs to some extent supplement its silk. A month later, the Bombyx appears.
In his final dimensions, the caterpillar measures nearly an inch and a quarter in length. His costume does not lack richness or originality: a black skin with a double row of orange specks on the back; long grey hairs arranged in bunches; short, snow-white tufts on the sides; and a couple of brown-velvet protuberances on the first two rings of the abdomen and also on the last ring but one.