Saturnia pavonia-major comes from a very large caterpillar, which is of a beautiful green, with tubercles of turquoise blue, each of which is surmounted by seven stiff divergent hairs. This caterpillar lives principally upon the elm, but it feeds also upon the leaves of the pear, plum, and other trees. It spins a brown cocoon, formed of a coarse silk of great strength. It is not until the following spring that it becomes a moth.
The Emperor Moth (Saturnia carpini, [Fig. 230]) much resembles the above, except in size. This species is common in England, and its green larva, covered with black or pink warts, from which spring hairs, as in the last, is by no means rare on heath in the autumn. It also feeds on bramble and other plants.
Fig. 230.—Emperor Moth (Saturnia carpini).
Among the Attaci foreign to Europe, we must mention Atlas ([Fig. 231]), the expanse of whose wings exceeds four and a quarter inches. This magnificent moth, one of the largest known, comes from China.
The family Bombycidæ comprises many species which we must not omit to mention.
The Lackey (Bombyx neustria) derives its name from the colour of the caterpillar, which has longitudinal lines of various colours, and a blue head. These caterpillars live together on a great number of our forest and garden trees, to which they do much damage. The moth ([Fig. 232]) has a brownish body, and wings of a more or less tawny yellow colour, with two darker lines on the front wings.
The Procession Moth (Bombyx processionea) is a small greyish moth, the caterpillars of which live in numerous troops on oak trees, and devour the leaves at the moment of their development. In the evening these caterpillars come out of their common nest, and form a sort of procession; hence their name Procession Moth. "I kept some for a little time in my house in the country," says Réaumur. "I brought an oak branch which was covered with them into my study, where I could much better follow the order and regularity of their march than I could have done in the woods. I was very much amused and pleased at watching them for many days. I hung the branch on which I had brought them against one of my window shutters. When the leaves were dried up, when they had become too hard for the jaws of the caterpillars, they tried to go and seek better food elsewhere. One set himself in motion, a second followed at his tail, a third followed this one, and so on. They began to defile and march up the shutter, but being so near to each other that the head of the second touched the tail of the first. The single file was throughout continuous; it formed a perfect string of caterpillars of about two feet in length, after which the line was doubled. There two caterpillars marched abreast, but as near the one which preceded them as those who were marching in single file were to each other. After a few rows of our processionists who were two abreast, came the rows of three abreast; after a few of these came those which were four abreast; then there were those of five, others of six, others of seven, others of eight caterpillars. This troop, so well marshalled, was led by the first. Did it halt, all the others halted; did it again begin to march, all the others set themselves in motion, and followed with the greatest precision.... That which went on in my study goes on every day in the woods where these caterpillars live.... When it is near sunset you may see one caterpillar coming out of any of the nests, by the opening which is at the top, which would hardly afford space for two to come out abreast. As soon as it has emerged from the nest, it is followed by many others in single file; when it has got about two feet from the nest, it makes a pause, during which those who are still in the nest continue to come out; they fall into their ranks, the battalion is formed; at last the leader sets off marching again, and all the others follow him. That which goes on in this nest takes place in all the neighbouring nests; all are evacuated at the same time."