A CHAPTER OF LIFE-HISTORIES. 
69 
slit thus made, a larger and handsomer caterpillar. 
It moults in this way twice more, and at last looks like 
Fig. 64, having a pair of horns at each end of its body 
and being striped with black, white, and yellow. 
It will be noticed that its first three pairs of legs are 
jointed and furnished with claws. The other legs, ten 
in number, are merely 
fleshy prolongations of 
the skin, provided with 
suckers or hooks to aid 
in crawling. These are 
called pro-legs, to distin¬ 
guish them from the three 
pairs of jointed legs com¬ 
mon to all Insecta. Its 
mouth is provided with strong mandibles, and its 
digesting power is enormous. The caterpillar has now 
reached a length of two inches. After a little time it 
again becomes restless, leaves the plant on which it 
has so far lived, and lodges on a neighboring fence or 
stump. Here it spins a little silk, entangles its hind 
legs in the threads thus produced, and hangs head 
downward for a day and a night. Its skin then splits 
along the back and the caterpillar performs the difficult 
feat of crawling entirely out of its old covering without 
the use of legs or mandibles, for these 
disappear with the old skin. The little 
spike at the end of its tail is fastened 
into the web of silk, and its body sus¬ 
pended thereby for a period of rest. The 
skin hardens and the rich ornamentation 
FlG ; Pu P a of green, black, and gold appears. We 
butterfly, one a° not wonder that it is called a chrysa- 
half natural Hs (Fig. 65). 
size. After There is now no mouth for feeding, 
for the mouth-parts are undergoing a 
wonderful change just beneath the skin. The maxillae 
elongate to form a proboscis, the wings appear and 
Fig. 64. — Larva of Milkweed- 
butterfly, one half natural size. 
After Riley. 
