ARTHROPODA. 



2 99 



mosquito larva does not cease to be active, but by a series of moults comes 

 to the so-called pupa stage from which by an early moulting the adult 

 mosquito emerges, balancing itself on the floating pupal skin until its wings 

 are hardened sufficiently for use. See Fig. 141. 



FIG. 143. 



c 



FIG. 143. The Cabbage Worm (Pieris rapa). Natural size. Photo by Folsom. A and 



B, larvae; 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. 144. 



FIG. 144. The adult Cabbage Butterfly (Pieris rapcr). Natural size. Photo by Folsom. 



Questions on the figure. Why is the larva of this animal called the 

 cabbage worm? Why is the adult called the cabbage butterfly? What 

 are its feeding habits? 



The Hessian-fly deposits its eggs in the tissues of growing wheat and 

 corn ; the clover-gnat and others produce galls which interfere with the 

 growth of the plant, often very seriously. In the case of the Hessian-fly 

 great damage to the wheat crop often results. See Fig. 142. 



