134 NORTH AMERICAN INSECTS. 
under lip, between which are skarp, horny jaws, with which 
they cut transversely the leaves, beginning at the margin. 
They cut with their jaws as easily and in the same manner 
as we do with scissors. 
Although we can not distinguish in them any organ of 
vision, it is more than probable that they are provided with 
eyes; for if we examine them with a magnifying glass we 
discover on each side of the head six black spots in a circle, 
which seem to answer the organ of sight; and if we ap- 
proach them in the night with a light, they imme¢iately 
begin to move, which shows that they must have some 
means of being affected by the light. Besides, their mo- 
tions in various voluntary directions testify much in favor 
of such an opinion, although it is possible that these may 
be detected by their exquisite sense of smell. 
There is no caterpillar which does not spin a web of 
some kind, by issuing a thread from a fleshy point of the 
under lip. 
Bopy.—The body of a caterpillar consists of twelve 
ringlets, upon nine of which, on each side of the ventral 
portion of the body, is seen an oval spot, surrounded some- 
times with a red or yellow ring. These oval spots are the 
respiratory organs by which the insect breathes. That 
these are the real respiratory organs is proved by putting 
oil or any greasy substance over these air-holes, the conse- 
quence of which will be immediate death by suffocation. 
Moreover, if a caterpillar is put under water or alcohol, 
air-bubbles will be seen issuing from innumerable minute 
holes in all parts of its body; and when the skin is taken 
off from the insect and held up against the light, the holes 
may be distinctly recognized, and the whole skin will ap- 
pear as if it were perforated with an immense number of 
fine pricks. 
Inside of the body, every caterpillar has a stomach, a 
heart, an intestine, and two long serpentine organs, which ex- 
