126 ECONOMIC ENTOMOLOGY 



San Jose Scale {Aspidiotus perniciosus Comst.). — China is probably 

 the home of this scale. It became estabhshed at San Jose, Cal., about 

 1870, and was introduced into Eastern nurseries in the U. S. about 

 1886-7, and into Ontario about 1896. Occurs on orchard trees, 

 bush fruits, and many perennials and annuals. On badly infested 

 branches the scale presents the appearance of dark-grey scurfy patches, 

 and on fruit there is often a purplish discoloration about the scale. 



Adult.— Th.e. female scale is circular, ^-'5 inch in diameter, with a 

 central exuvium surrounded by a yellowish ring. The male scale is 



Fig. 78. — a, Winged San Jose scale (much enlarged) ; b, young scale insect (enlarged 



125 times). 



oval, twice as long as broad, with a long dark exuvium showing a 

 nipple toward the small end of the scale. The San Jose scale winters in 

 the half-grown state. Early in spring the winged males appear, and 

 the females resume growth. The male moults thrice and the female 

 twice. In early June the females begin to produce living young. The 

 period of production lasts about six weeks during which time each 

 female produces on an average 400 young. The females mature in 

 35 to 40 days, and the males in about 25 days after their birth. There 

 are three or four broods in northern orchards (Figs. 77 and 78). 



Nymphs. — The half-grown scale is black, and shows a central nipple 

 surrounded by one or two depressed rings. 



Parasites. — The following Lady-birds feed on the San Jose Scale: 

 Chilocorus bivulnerus, Pentilia misella and P. suturalis. 



