134 NORTH AMERICAN INSECTS. 



under lip, between which are sharp, 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 immediately 

 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. 



Body. — 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- 



