INSECTS INJURIOUS TO ORCHARD FRUITS 471 



Injury by this species was first noticed near San Jose, Cal., 

 about 1880, where the scale was most destructive and was inves- 

 tigated by Professor J. H. Comstock, who first described it. 

 About 1887 it was brought east on Japanese plum trees secured 

 by Eastern nurseries and was distributed by them on young 



FIG. 394. Peach twigs infested with the San Jose scale. On the twig at 

 the right a scale has been turned back showing the female insect 

 enlarged. (After W. E. Britton.) . 



trees, so that in 1893 it was discovered in orchards in Maryland 

 and Virginia. Since then it has been spread on nursery trees to 

 practically every State. Investigations made by C. L. Marlatt 

 in 1901 showed that the insect is undoubtedly a native of east- 



