THE LIFE HISTORY. 9 
thirteenth segments —the fifth, sixth, eleventh and twelfth seg- 
ments having none. A number of caterpillars, however, have but 
four pairs of claspers (also called abdominal legs or prolegs), while a 
few have but two pairs, and these situated at the extremity of the 
body. The claspers are thick and fleshy, and may be extended or 
contracted, while their ends are surrounded with a number of minute 
hooks. These prolegs or claspers are absorbed into the abdomen of 
the insect during its transformation into a pupa. 
In walking, a caterpillar advances by an undulating motion, 
extending and contracting its body. A few species (the geometrids) 
advance by bending the body up into a loop and then extending it to 
its full leneth. These are sometimes called inch-worms or measure- 
worms, from their mode of progression. 
Insects breathe through spiracles or air-tubes in their sides; and 
the openings of these tubes are often plainly visible in caterpillars, 
especially in smooth ones. They are located on the segments, one 
on either side, and are often enclosed in a small circular or oval 
patch of color. 
The variety of the shapes and colors of caterpillars is well-nigh 
endless, and often most wonderful, they being adapted in many 
instances to so resemble the plants upon which they feed that their 
enemies are baffled in their search for them. 
Some look and act as if they were venomous, while others are by 
their repulsive or even terrible appearance calculated to frighten 
insect-devouring creatures. Some are smooth-skinned, some humped, 
or covered with bunches, tubercles, warts, fleshy filaments, horns, 
spikes, spines, bristles, hairs or down, and sometimes a combination 
of several of these. A few sting like the nettle, while others shed 
their sharp pointed hairs which work into the flesh if they are 
roughly handled. Some secrete strong, disagreeable odors, while 
some are perfumed like a dandy at a ball. Their colors are scarcely 
less wonderful. Some bear large spots which look like great eyes 
watching from the leaves. Some are striped or banded, or sprinkled 
with dots. They are of every imaginable color or shade, but the 
majority are green, and so nearly resemble the leaves among which 
they feed that it is difficult to see them. Some look as if made of 
bark and covered with lichens; others so closely resemble twigs with 
their minute knots as to deceive even the expert. : 
But with all these subterfuges for protection, the birds, toads and 
ichneumon flies find most of them out; thus, in spite of the countless 
