But the life of a caterpillar, after all, is not merely the smooth continual feast he would doubtless prefer it to be; it is interrupted, several times in its course, by the necessity nature has imposed upon him of now and then changing his coat—to him a very troublesome, if not a painful affair.
For some time previous to this phenomenon, even eating is nearly or quite suspended,—the caterpillar becomes sluggish and shy, creeping away into some more secluded spot, and there remaining till his time of trouble is over. Various twitchings and contortions of the body now testify to the mal-aise of the creature in his old coat, which, though formed of a material capable of a moderate amount of stretching, soon becomes outgrown, and most uncomfortably tight-fitting, with such a quick-growing person inside it: so off it must come, but it being unprovided with buttons, there's the rub. However, with a great deal of fidgeting and shoulder-shrugging, he manages to tear his coat down the back, and lastly, by patient efforts, shuffles off the old rag;
when, lo! underneath is a lustrous new garment, somewhat similar, but not exactly a copy of the last, for our beau has his peculiar dress for each epoch of his life,—the most splendid being often reserved for the last.
This change of dress ("moulting," it is sometimes called) is repeated thrice at least in the creature's life, but more generally five or six times. Not only does the outer husk come off at these times, but, wonderful to relate! the lining membrane of all the digestive passages, and of the larger breathing tubes, is cast off and renewed also.
After each moult, the caterpillar makes up for his loss of time by eating more voraciously even than before, in many instances breaking his fast by making a meal of his "old clo'"—an odd taste, first evinced, as we have seen, in earliest infancy, when he swallowed his cradle.
On [Plate I]. are shown the chief varieties of form taken by the caterpillars of our British butterflies, and a glance at these will give, better than verbal descriptions, a general idea of their characteristics.
Their most usual shape is elongated and almost cylindrical, or slightly tapering at one or both ends. Of these, some are smooth, or only studded with short down or hairs; such are the caterpillars of the Swallow-tail butterfly (fig. 1), of the Brimstone (fig. 2), Clouded Yellows, and Garden, and other white butterflies. Others, of the same general form, are beset with long branched spines, making perfect chevaux-de-frise; such
are those of the Peacock, Red Admiral, Painted Lady, and the Silvery Fritillaries.
The caterpillars of another large section have the body considerably thicker in the middle (rolling-pin shaped), and the tail part two-forked, or bifurcate. This form belongs to the numerous family that includes the Meadow-brown (fig. 3), the Ringlets, and many others.
The bizarre personage, at fig. 4, turns to the graceful White Admiral butterfly.