158 INSECT PESTS OF BERRIES AND GRAPES 



is one twenty-fifth of an inch long; light greenish yellow in summer, 

 and darker in winter. When they are numerous on the roots there 

 is an appearance as if the roots were dusted with mustard. 



Life History. There are really four forms to be observed in 

 the life history of this plant louse: (1) the leaf -gall form; (2) the 

 root form, which is the most destructive; (3) the winged or coloniz- 

 ing form; and (4) the sexual form. Winter eggs are deposited in 

 the fall on bark or wood. They hatch in the spring, and the 



FIG. 175. The rose-chafer or rose-bug; different stages, details of structure and injury to 

 grape leaf. (U. S. Bu. Ent.) 



young, settling on the leaves, cause galls on the lower side. These 

 are all females, which die after laying their eggs. In about eight 

 days these eggs hatch into females like the parent, which migrate 

 and form new galls. There may be six or seven generations during 

 the season. Many migrate to roots during the spring and summer, 

 and they all seek the roots at the approach of winter. The last 

 generation takes no food, and each female lays one egg, which 

 passes through the winter. 



The next spring the roots are attacked and the females multiply 



