232 



ELEMENTARY ENTOMOLOGY 



attention as they flit over rank-growing foliage in damp places. The 

 adults feed on small flies, and the larvae live underground, being 



either predacious or feeding on 

 decaying vegetable matter. 



The wasp-flies (Conopidae) 

 should also be mentioned, on 

 account of their close resem- 

 blance to wasps, with which 

 they may readily be confused at 

 first glance, and which they 

 undoubtedly mimic. They are 

 narrow-waisted, the tip of the 

 abdomen is like that of a wasp, 

 and they are often banded and 

 colored to heighten the likeness. 



FIG. 366. A long-legged fly (Psilopo- . 1-11 



dinus sipho] * ne neacl is robust, which has 



(After Lugger) given them the common name 



of "thick-headed flies." The 



larvae are parasitic within the bodies of 



wasps, bumble-bees, and grasshoppers, on 



which the eggs are laid. The adults feed on 



nectar and pollen of flowers, over which they 



may be found hovering. 



The flower-flies (Syrphidae) are medium- 

 to-large-sized, bright-colored flies which feed 



upon nectar and pollen of flowers, over 



which they may be seen 

 to hover, almost motion- 

 less, for several seconds 

 and then to dart off and 

 as quickly return. These 



flies may be readily recognized by a thicken- 

 ing which looks like a vein extending across 

 the middle of the wing. Our more common 

 species of the genus SyrpJins have the abdo- 

 men marked with alternate bands of black and 

 yellow, and have greenish, bronze, or yellowish 

 bodies. They lay their small, oval, white eggs 



FIG. 367. A wasplike 



fly (Physocephala tiffin is). 



(One and one half times 



natural size) 



(After Kellogg) 



FIG. 368. The bee- 

 fly (Eristalis tenax). 

 (Natural size) 



