304 



ZOOLOGY 



The caterpillars are usually voracious and may strip their food plant of its 

 leaves and buds. The majority of the larvas have become highly specialized in 

 their food habits, becoming restricted in some instances to one species or to a few 

 related species (as illustrated by the tomato worm, which feeds on tomato, potato, 



Pig. 145. 



Fig. 145. The Cabbage Worm (P(eri5 roptsj. Natural size. Photo by Folsom. A and i3, larvje; 



C, pupa. 



Questions on the figure. — What is a larva? What is a pupa? Which is the 

 earlier stage? What is the color of this caterpillar in nature? See the next 

 figure for the adult. 



Fig. 146. 



Flc. 146. The adult Cabbage Butterfly (Pieris raixs). Natural size. Photo by Folsom. 



Questions on the figure. — Why is the larva of this animal calledthe cabbage 

 worm? Why is the adult called the cabbage butterfly? What are its feeding 

 habits? 



and tobacco leaves; or the cabbage worm which eats the leaves of certaiOj^of the 

 cruciferous plants). The distribution of such species is thus clearly determined 

 by that of their host plants. Among the most, injurious to vegetation are the 

 "tent-caterpillars" which occur gregariously and spin a web-like nest; the army- 

 worm so-called because it sometimes appears and moves from its hatching grounds 



