THE FLIES: DIPTERA 



73 



Hover Flies. Often a collector captures an insect flying 

 about flowers which has the characteristic manner and yel- 

 low and black colors of a wasp, but which has only two 

 wings. It is one of the hover flies, many of which afford 

 illustrations of protective mimicry. Some species of Eris'- 

 talis (Fig. 57) mimic 

 the male honeybee 

 and are therefore 

 named drone flies ; 

 others belonging to 

 Volucel'la (Fig. 57) 

 mimic bumblebees. 

 The larvae of some 

 feed chiefly upon 

 aphids and are there- 

 fore beneficial to the 

 farmer; yet others 

 inhabit pools of stag- 

 nant water or decay- 

 ing wood. 



Mosquitoes. The 

 mosquitoes comprise Fig. 49. Development of mosquito. (Enlarged) 

 a group Widely dis- A, egg mass; B, larva; C, pupa. (After Howard, 



tributed over the 

 tropical and temper- 

 ate regions of both hemispheres. In nearly all the species 

 observed the mouth parts of the females only are fitted 

 for piercing the skin of animals. The males, if they feed at 

 all, probably suck the fluids of plants ; in fact, both sexes 

 in the past history of the race were probably, and are 

 still, to some extent, plant feeders. 



A common mosquito of the Mississippi Valley and the 

 East is Cu'lex pip'iens. The female lays her eggs (Fig. 49) 

 in irregular masses containing over two hundred eggs, on 



Bulletin No. 25, N.S., United States Department 

 of Agriculture, Division of Entomology) 



