12 NSECT PESTS OF FARM, GARDEN AND ORCHARD 



But the larvae of possibly the 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 larvae 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 larvae at once commence crawling over the plant in search 

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

 is firmly clasped by the small booklets until the juices are sucked 

 from its body. In this manner very large numbers are destroyed, 

 a single maggot of the American Syrphus-fly (Syrphus americanus) 

 having been observed to eat twenty-five apple plant-lice (Aphis 

 pomi) in as many minutes. When the larva is ready to pupate 

 it attaches itself tc a leaf, and the larval skin dries up and forms 

 a case or puparium inside of which the pupa remains until it 

 transforms to the adult fly. 



Though most of these larvae feed upon plant-lice upon the 

 leaves, one of them, the Root-louse Syrphus-fly (Pipiza radicans), 



FIG. 7. The root-louse syrphus-fly (Pipiza radicans). a. maggot: b, puparium: 

 c, fly. (After Riley.) 



lives entirely underground during that stage, and feeds upon 

 the root-lice of the apple and the grape. None of this family 

 is injurious, and as a large portion of them are so beneficial 



