276 INSECT PESTS OP FARM, GARDEN AND ORCHARD 



found in the crevices and around the buds of the terminal twigs 

 of plum-trees near infested hop-fields. From these hatch a 



FIG. 202. The hop-louse (Phorodon humuli Schr.) : a, winter eggs and shrivelled 

 skin of the sexual female which laid them; 6, stem-mother, or first spring 

 generation, with enlarged antenna above all much enlarged. (After 

 Riley, U. S. Dept. Agr.) 



FIG. 203. The hop plant-louse, third generation on plum the generation 

 which flies to the hop enlarged; head below at right still more 

 enlarged. (After Riley, U. S. Dept. Agr.) 



generation of females, known as " stem-mothers," during the 

 following spring. The aphides of this generation differ in being 

 stouter, with shorter legs and honey-tubes than those of any other 



