190 NORTH AMERICAN INSECTS. 



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 serpent inetubes, 

 which extend to the hind part of the body, and thence 

 back to the neck, where they open at the inferior lip. 

 Those tubes contain the substance which the animal 

 uses in spinning, which is a yellow or white juice, ac- 

 cording to the food it takes, and upon this also, pro- 

 bably depends the fineness of the silk they make, in 

 the same manner as the quality and color of butter 

 depends upon the food of the cow. 



These tubes joining together and opening at the 

 under lip, constitute the spinning apparatus of cater- 

 pillars, and may be distinctly seen by opening w ith 

 great care and caution, the back of the animal. The 

 juice contained in the tubes is nothing more nor less 

 than a kind of very fine varnish, of which the people 

 of some countries make use, but which no one has yet 

 undertaken to use in this country. Should this var- 

 nish ever come into general use, our most noxious 

 caterpillars would become beneficial to us. 



The single parts of Moths and Butterflies, although not 

 quite as varied and complex as those of caterpillars, 

 still present some points of interest and curiosity, and 

 far excel them in beauty and splendor. 



