318 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



pale shanks, the pupa? with a row of mealy white spots along each 

 side of the back." Fitch. 



This is an old European pest of the bean, where it is known as 

 the black dolphin, collier, and black fly, and has sometimes 

 caused the entire destruction of a crop. In the United States 

 it probably occurs wherever beans are grown, having been reported 

 from Xew York, Illinois, Iowa, Minnesota and Colorado. The 

 species is probably best known as affecting various species of 

 dock, upon the leaves of which it occurs commonly in large num- 

 bers. Shepherd's purse, pigweed, the " burning bush " (Euony- 

 mus europoeus and atropurpurus), and the snowball bush are also 

 commonly infested. 



Life History. The life history was first described most inter- 

 estingly by Dr. Fitch in his 13th Report * and has since been 

 confirmed by Osbornc and Sirrine.f The eggs are laid in the fall 

 around the buds of the wahoo or " burning bush " (Euonymus 

 atropurpurus), and possibly upon the snowball. The first gen- 

 eration or two multiply upon these plants and then spread to 

 common weeds such as shepherd's purse, pigweed, dock, etc. 

 during the latter part of May and early June, from which they 

 again migrate to beans when that crop is available. During 

 the summer the aphides multiply upon these food-plants vivipar- 

 ously, i.e., by giving birth to live young, all being females, as is the 

 rule with aphides; but about the middle of September, in Iowa, 

 winged males and females migrate back to the wahoo. 



Description. The wingless females are about one-tenth an 

 inch long, pear-shaped, sooty black, frequently marked with 

 pruinose whitish dots along each side of the back. The antennse 

 are about half the length of the body, yellowish-white, except 

 toward the tips and the two basal segments, which are black. 

 Honey tubes short, scarcely half as long as from their bases to 

 tip of abdomen. Tail half as long as the honey tubes. 



The winged females are glossy black, one-twelfth an inch 



* Fiteh, 13th Report on the Noxious, Beneficial and other Insects of the 

 State of Xew York, Trans. N. Y. State Agr. Soc., 1869, p. 495. 



t Osborn and Sirrine, Bulletin 23, Iowa Agr. Exp. Sta., p. 901, 1894. 



