BENEFICIAL INSECTS, PREDACEOUS AND PARASITIC 13 



Syrphus-flies 



Besides the little beetles described above there is a family 

 of flies, the Syrphidce, many of whose larvse feed upon plant- 

 lice. This family is a very large one, and thus the habits of its 

 different members vary considerably. One of them, the drone- 

 fly, so closely resembles a honey- 

 bee as to be almost indistin- 

 guishable from it. The larva of 

 this fly (Eristalis tenax) is one 

 of the common rat-tailed mag- 

 gots which are found in putrid 

 matter. It is thought that the 



Old "bugonia" superstition of FJG ^-Syrphus ribesii- enlarged. 

 the ancients that bees came from 



maggots in dead aninmals, etc., was due to the confusion of this 

 fly with honey-bee. 



In another group of the family, the adult flies of which also 

 quite closely resemble bees, the larvae are parasitic in the nests 

 of honey- and bumble-bees, feeding upon their larvse. 



But the larvse of possibly the most typical portion of the 

 family, embracing the genus Syrphus and its near allies, are 

 entirely predaceous upon plant-lice. Rarely can a colony of 

 plant-lice be found without some of these little enemies hard 

 after them. 



The adult syrphus-fly is a very striking insect, with its dark 

 green metallic thorax, and abdomen variously banded with 

 yellow and black. The female fly lays her eggs upon some plant 

 bearing plant-lice. The larvse which hatch from these are elongate, 

 flattened maggots, about one-half an inch long, with hardly a 

 trace of a head, but with four small hooks, which serve as jaws, 

 projecting from the more pointed end of the body. These mag- 

 gots are often of a light-green color, and so like the color of 

 the plants as to render them most difficult to recognize. The 

 young larvse at once commence crawling over the plant in search 

 of aphids, and as soon as they come in contact with one it 



