59 
The largest scales are about the size of the head of an ordinary 
pin, and the smallest ones are mere specks on the twig. 
This insect passes the winter partly grown, reaches its full size 
in spring, and begins to bring forth its living young about the first 
of June, in average years, in the central part of Illinois. These may 
be seen as minute yellow specks wandering over the surface in searcli 
of a suitable place to establish themselves. This period of active 
life is often limited to a few hours, and at most to one or two days. 
Three or four ^fenerations are hred in a sinsfle season. 
Fig. 62. San Jose Scale, Aspidiotus 
permciosus. Natural size. (Connec- 
ticut Experiment Station.) 
It has been found commonly infesting and often injuring more 
than seventy trees and shrubs, and occasionally nearly as many 
more. The commoner kinds coming under the former list are some 
of the dogwoods, the hawthorns { Cratcrgits) , the quinces, the pop- 
lars, the cherries and pears, currants and gooseberries, roses, willows, 
mountain ash, snowberry, lilac, basswood, Osage orange, and the 
elms. Those less seriously infested are the maples, horse-chestnut, 
Virginia creeper, the birches, chestnut, catalpa, hackberry, the flow- 
ering and other dogwoods, the persimmon, Forsythia, white ash. 
