128 NORTH AMERICAN INSECTS. 



Caterpillars very often inform us as to the properties of 

 the plants upon which they feed; thus the Potato-worm 

 (Sphinx Carolina) feeds only upon the different species of the 

 night-shade tribe (Solanece) ; for instance, on the egg-plant, 

 the potato and tomato-vine, etc. ; the Asterias (Papilio as- 

 terias) lives upon the leaves of the umbrella tribe ( Umlelli- 

 ferce), as the parsnep, cicuta, parsley, caraway, anise, cel- 

 ery, etc. ; and the Danaus (Danaus plexippus) feeds only 

 upon the different species of milk-weed. 



The excrement of caterpillars furnishes an excellent 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 manu- 

 facture their cocoons ; and to obtain 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 substance is skimmed off, and proves a 

 valuable varnish. It is said that the Japanese use this to 

 varnish their finest fancy articles. 



Raising caterpillars for the purpose of obtaining from 

 them perfect butterflies or moths is not only an agreeable 

 and instructive operation for young pupils in their leisure 

 hours, but it has often been a very lucrative business. In 

 Altona, in Denmark, I became acquainted with a gentle- 

 man who raised in his conservatory several species of the 

 large moths, natives of North America as the Cecropia, 

 Luna, Polyphemus, and Promethea which he sold readily 

 at two dollars apiece, and of which he raised on an average 

 a thousand specimens a year. 



Caterpillars are of quite an important use to man as the 

 principal food of birds, and the amount of good they do in 

 yielding up their lives as nourishment for others would as- 

 tonish one unaccustomed to reflect upon the subject, and 

 really goes far toward compensating the injury they do to 

 vegetation. There are at least 1200 species of lepidop- 



