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BULLETIN OF 

 MASSACHUSETTS BOARD OF AGRICULTURE. 



The San Jose Scale. (Aspidiotus pernicio^us Com.) 



Bt C. H. Feenald, Entomologist to the Board. 



History and Distribution. 



The San Jos6 (San Ho-sa ) scale insect first made its appearance 

 in California not far from 1870, but it is not known from what 

 country it came, though it is now known to occur in Chili, Aus- 

 tralia and Hawaii. It increased rapidly till 1873, when it had 

 become so abundant on the fruit trees at San Jos6 as to seriously 

 injure them, and received the common name of the San Jose scale. 



It was first technically named and described from Santa Clara 

 County, California, by Prof. J. H. Comstock, in the report of the 

 Department of Agriculture for the year 1880, page 304, under the 

 name Aspidiotus perniciosus, " The Pernicious Scale." After 

 describing it. Professor Comstock says : " From what I have seen 

 of it, I think that it is the most pernicious scale insect known in 

 this country ; certainly I never saw another species so abundant as 

 this one is in certain orchards which I have visited. It is said to 

 infest all the deciduous fruits grown in California, excepting the 

 peach, apricot and the black tartarian cherry. It attacks the 

 bark of the trunk and limbs as well as the leaves and fruit. I 

 have seen many plum and apple trees upon which all the fruit was 

 so badly infested that it was unmarketable." Since Professor 

 Comstock wrote the above, the insect has been found on apricot 

 and peach as well as other plants. 



In 1882 it had extended into all the fruit-growing districts of 

 California, and has since that time been distributed over the 

 country more or less widely, and is now known to occur in Oregon, 

 Washington, British Columbia, Idaho, Nevada, Arizona, New 

 Mexico, Missouri, Indiana, Florida, Virginia, Maryland, Pennsyl- 

 vania, New Jersey, New York and Massachusetts. It does not 

 appear to be very generally distributed as yet in the Eastern 



