INSECTS INJURIOUS TO BEANS AND PEAS 323 



Carolina to Nova Scotia and as far west as Wisconsin, especially 

 where peas were extensively grown for canning. During 1901 

 injury was by no means as serious, and has materially decreased 

 since then, though sporadic injury occurs almost every year in some 

 section. General injury occurs only periodically for reasons men- 

 tioned below. The pest seems to occur throughout the States east 

 of the 100th meridian and possibly further west. It is an old 

 enemy of peas in England, where it destroyed the crop as long ago 

 as 1810, and it has long been known in Europe as an enemy of 

 peas, clovers, vetches and related plants. 



Both wingless and winged aphides occur together throughout 

 the season, the latter predominating whenever food becomes scarce. 

 The winged forms are from one-eighth to one-seventh of an inch 

 long, with wings expanding two-fifths of an inch. The body is a 

 pea-green color, light brownish between the wings and on the head, 

 the eyes are red, and the legs, antennae and honey tubes are yellow- 

 ish, tipped with black. The wingless females are similar in size and 

 color, but are much broader across the abdomen, and the honey 

 tubes are somewhat larger. The mouth-parts of the pea-aphis are 

 of the sucking type, and it secures its food by puncturing and suck- 

 ing up the juices of the plant. The plant is thus injured by the 

 large number of aphides sucking out its juices and causing it to 

 wilt and die. 



Life History. The aphides pass the winter on clover and 

 vetches, and often increase upon clover so as to do it serious 

 injury, as described on page 211. Where peas area vailable the 

 winged females usually migrate to them about the time peas are 

 6 or 8 inches high, and give birth to live young, which develop into 

 wingless viviparous females. These females, as do those of sub- 

 sequent broods throughout the summer, give birth to live young, 

 and reproduction goes on at a rapid rate. According to the obser- ' 

 vations of Mr. R. L. Webster, in central Illinois, an aphid becomes 

 grown about eleven days after it is born, lives about twenty-five 

 -days and gives birth to about fifty young, though under favorable 

 conditions over one hundred are frequently born. Sixteen genera- 

 tions have been observed from March 23d to October 4th. Winged 



