180 NORTH AMERICAN INSECTS. 



generally despised on account of the immense injury 

 they do to vegetation, but the prevailing prejudice 

 against them, in my opinion, arises more from the 

 general ignorance of their uses, and the benefit they 

 are capable of confering upon man, than upon the 

 actual amount of damage done by them. We will 

 mention some of their uses, and again endeavor to 

 convince our readers that none of the works of na- 

 ture are so insignificant as to be wholly without use 

 in the great plan of economy. 



Caterpillars very often inform us as to the proper- 

 ties of the plants upon which they feed ; thus the po- 

 tato-worm, Sphinx Carolina, feeds only upon the dif- 

 ferent species of the night shade tribe, (Solaneae), for 

 instance, on the egg- plant, the potatoe and tomato 

 vine, &c. ; the Asterias (Papilio Asterias) lives upon 

 the leaves of the umbrella tribe (Umbelliferae) ; as 

 the parsnip, cicuta, parsley, caraway, anise, celery, &c. ; 

 and the Danaus (Danaus Plexippus) feeds only upon 

 the different species of milk-weed. 



The excrement of caterpillars furnishes an excel- 

 lent dye-stuff, and their bodies the finest of varnish. 

 It is well known that the body of each caterpillar is 

 provided with a glutinous substance by which they 

 are enabled to manufacture their cocoons, and to ob- 

 tain this they are collected in many countries in large 

 quantities and boiled in water until a greasy liquor 

 is seen floating upon the surface. This oleaginous 



