134 THE SPRING GRAIN-APHIS OR " GREEN BUG." 



This little fellow goes about getting its meals in a very quiet, 

 unobtrusive sort of way. It crawls quietly up among a number of 

 Toxoptera and the first one it touches becomes its victim. It at- 

 taches its mouthparts to some joint of the legs, usually at the artic- 

 ulation of the femur and tibia, and sucks out the juices of the 

 aphidid. With a compound miscroscope the blood can readily be seen 

 flowing in a constant stream, through the limb of the aphidid attacked, 

 into the larva of the cecidomyiid. Rarely is the aphid disturbed 

 and upon close observation the skin of the aphidid will be seen to 



Fig. 47.— Aphidoletcs sp., cecidomyiid fly whose larvae feed upon the spring grain-aphis. Greatly 



enlarged. (Original.) 



gradually shrivel up; finally nothing but the empty skin remains and 

 the larva crawls away in search of more aphidids, frequently with 

 the old empty aphidid skin adhering to it. The time required to 

 consume the juices of an aphidid varies with the size of the larva 

 and of the aphidid. A larva that is about full grown can dispatch 

 a small aphidid in a few minutes, while from 15 to 30 minutes are 

 required for it to empty a full-grown one. These cecidomyiid larvae 

 have enormous appetites and apparently keep up their work of 

 destruction almost constantly until they become full grown. 



It is not at all impossible for this insect to become a very im- 

 portant factor in the control of Toxoptera, as the adults are capable 

 of flight and deposit large numbers of eggs. 



