530 INSECT PESTS OF FARM, GARDEN AND ORCHARB 



infested foliage and upon it there grows a blackish fungus which 

 gives the leaves a sooty appearance, often visible on the twigs 

 after they drop, and a good indication of injury by this species. 

 The full-grown wingless females are about one-twelfth inch long, 

 and shaped as shown in Fig. 457. They are of a bright green 

 color, though occasionally yellowish, and the tips of the ant- 

 ennae, honey-tubes, and tail are black. The winged female is 

 slightly longer and the wings expand about one-quarter inch, 

 the head is deep olive brown; the thorax is blackish, and there 

 are three black spots on the lateral margin of the abdomen, 

 but otherwise it is colored like the wingless female. 



FIG. 459. Nymphs of the apple-aphis, clustered on a leaf, showing developing 



wing-pads. 



Life History. The minute, oval, shining black eggs are to 

 be found on the twigs during the winter, especially at the 

 crotches and around buds and scars. They hatch just before 

 the leaf buds open and the young aphids become full grown in 

 two or three weeks, all of them being wingless. During the next 

 two or three weeks each of these females will give birth to from 

 50 to 100 young, a few of which develop wings. All of the aphids 

 of this second generation are also females, which give birth to 

 live young without the intervention of males, which do not appear 

 until fall. Their young develop in a week or ten days and most 

 of them become winged and migrate to other trees. The develop- 

 ment and reproduction continues in this fashion throughout the 

 summer, both winged and wingless females being found in most 

 colonies, though the size and coloration differ in the various 



