148 THE INSECT WORLD. 
its body, and carries its head as far forward as possible. The 
portion of the leaf which is between the open jaws is cut 
through the instant the teeth 
meet each other; the bites 
succeed each other quickly ; 
there is not one, or scarcely 
one of them, that does not 
detach a bit, and each bit is 
swallowed almost as soon as 
cut off. At each fresh bite, 
the head approaches the legs 
in such a way that during the 
succession of bites it describes 
Fig. 101.—Looper Caterpillar eating the leaves aids BIG | it hollows out the 
eR ne Ab Hicoe cater Reponiuy). portion of the leaf in a segment 
of a circle, and it is always in this order that it gnaws it.” 
But there is a phenomenon in the life of caterpillars which we 
ought to point out, and which has attracted the attention of the 
most illustrious observers. All caterpillars change their skins 
many times during their life. It is not, indeed, enough to say 
that they change their skins; the skins or cases they cast are so 
complete, that they might be taken for entire caterpillars. The 
hairs, the cases of the legs, the claws with which the legs are 
provided, the hard and solid parts which cover the head, the 
jaws,—all these are found in the skin which the insect abandons. 
What an operation for the poor little animal! This labour is so 
enormous, so troublesome, that one cannot form a just idea of it. 
One or two days before this grand crisis, the caterpillar leaves 
off eating, loses its usual activity, and becomes motionless and 
languid. Their colour fades, their skin dries little by little, they 
bow their backs, swell out their segments. At last this dried-up 
skin splits below the back, on the second or third ring, and lets 
us have a glimpse of a small portion of the new skin, easily to be 
recognised by the freshness and brightness of its colours. 
““When once the split has been begun,” says Réaumur, “it is 
easy for the insect to extend it; it continues to swell out that part 
of its body which is opposite the slit. Very soon this part raises 
itself above the sides of the split; it does the work of a wedge, 

