72 MANUAL OF VEGETABLE-GARDEN INSECTS 



recent years, it is still the most serious insect pest with which 

 pea-growers have to contend. In England the pea aphis has 

 been known as a pest since the early part of the nineteenth cen- 

 tury. It received the scientific name under which it is now 

 known in Germany in 1843, although it is quite probable that 

 it had been more or less imperfectly described previously. 



The pea aphis occurs generally throughout Europe and has 

 been introduced into British India and South Africa. In 

 North America it is widely distributed throughout the United 

 States and Canada, being most abundant in the East, but has 

 been reported from Colorado, Texas, New INIexico, Arizona 

 and the states on the Pacific Coast. In addition to the pea 

 the insect attacks red clover, crimson clover, white clover, 

 alsike, vetch, sweet pea, sweet clover, bush clover, alfalfa and 

 lentil. It als ) occasionally infests shepherd's purse. In 

 Europe the aphis has been recorded as feeding on several 

 other leguminous plants. 



The pea aphis usually passes the winter on clover and breed- 

 ing is resumed on this plant in the spring. At this time the 

 aphis shows a decided preference for crimson clover on which it 

 multiplies rapidly. In Virginia about the last of April or the 

 first of ]\Iay, winged aphids are produced that migrate to peas. 

 These migrating forms are all females that reproduce by giving 

 birth to living young without being fertilized. These winged 

 viviparous females (Fig. 49) are ^ to -g- inch in length, pea-green 

 in color, with the tip of the cornicles, tip of the tibi?e, and the 

 tarsi black. The eyes are red. The antenna? are slightly 

 longer than the body. The winged forms settle on the pea 

 plants, usually on the stem, and begin to give birth to living 

 young. In the course of its development, the young aphis 

 passes through four immature stages, molting four times, and 

 at the last molt becoming adult. On the average it requires 

 about ten days for the young aphis to reach maturity, and when 

 about twelve days old it begins to produce living young. Re- 



