No. 6. DEPARTMENT OF AGRICULTURE. 233 



TREATMENT FOR SAN JOSK SCALK IN OR- 

 CHARD AND NURSERY. 



Bv John B. Smith. S;;. D.. t:atoinolo(jUt of the Xew .Jirsf]i Kxperinunt Stution. 



The Sau Jose or reiiiicious Scale seems, from present evidence, 

 to be a native of Asia, occurring in Japan and China under such cir- 

 cumstances as to make it improbable that it could have been intro- 

 duced from any other country. It is only within the last year that 

 the matter has been fairly settled by the researches of Mr. C. L. Mar- 

 latt of the U. S. Department of Agriculture, and not the least im- 

 poitant of his observations is that, where the insect occurs naturally, 

 it is not injurious; that is, the insect and its host plants are so bal- 

 anced that both exist without inconveniencing each other. 



Mr. Marlatt's studies point to a species of lady-bird, closely allied 

 to our own twice-stabbed species, as the check that prevents un- 

 due increase, and the natural suggestion is. that this predatory 

 species be introduced into the United States to do for us what it does 

 in Asia — i. e., control the pernicious scale. Attempts in that direc- 

 tion are under way and will be again referred to. 



Just v.hen the insect was introduced into the United States, no one 

 knows definiteh'. It is probable that it was in 1870 or before. It is 

 certain that in 1S73 it was fullv established in the Santa Clara vallev, 

 in the vicinitv of San Jos^ from which the insect derives its common 

 name. 



HISTORY IN CALIFORNIA. 



Not until 18S0 did the insect come before the Entomologist for 

 study. In that year Prof. J. H. Comstock, then Entomologist to the 

 U. S. Department of Agriculture, determined that it was undescribed 

 and called Mperniciosus; basing his name upon the destruction which 



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