The Life-History and Anatomy of Butterflies 
caterpillar is crawling about from place to place. The larva 
appears to guide itself in great part by means of the palpi. 
The body of the caterpillar is covered by a thin skin, which 
often lies in wrinkled folds, admitting of great freedom of 
motion. The body is composed, as we have seen, of rings, or 
segments, the first three of which, back of the head, correspond 
Fig. 15.—Head 
of caterpillar of 
Anosia plexifi' 
pus , side view 
showing ocelli 
Fig i 6.—Caterpillar of Anosia plexippus, milkweed 
butterfly (Riley). 
to the thorax of the perfect insect and the last nine to the abdomen 
of the butterfly. On each ring, with the exception of the second, 
the third, and the last, there is found on either side a small oval 
opening known as a spiracle, through which the creature breathes. 
As a rule, the spiracles of the first and eleventh rings are larger in 
size than the others. 
Every caterpillar has on each of the first three segments a pair 
of legs, which are organs composed of three somewhat horny 
parts covered and bound together with skin, and armed at their 
extremities by a sharp claw (Fig. 17). These three pairs of feet 
in the caterpillar are always known as the fore legs, and corre- 
ieg of caterpil¬ 
lar of Vanes- 
sa antiop a,en- 
larged. 
Fig. 18.—Ante-’ 
rior segments of cat¬ 
erpillar of milkweed 
butterfly, showing 
thoracic or true legs 
(Riley). 
Fig. 19. —Proleg 
of caterpillar of 
Vanessa antiopa , 
enlarged. 
spond to the six which are found in the butterfly or the moth. 
In addition, in most cases, we find four pairs of prolegs on 
the under side of the segments from the sixth to the ninth, 
and another pair on the last segment, which latter pair are 
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