236 Peach-Growing 



A contact insecticide must be used in spraying for them, 

 a tobacco extract, of which there are several proprietary 

 preparations, commonly being advised. Spraying should 

 be done before the leaves become deformed; otherwise, 

 after they become curled and misshapen, it will be impos- 

 sible to reach the insects with the insecticide. 



San Jose scale {Aspidiotus perniciosus) 



Perhaps no other occurrence has ever so thoroughly stirred 

 peach-growers as did the appearance and wide dissemina- 

 tion of the San Jose scale during the 90 's and in the first 

 part of the decade beginning with 1901. During these 

 years this insect became generally distributed throughout 

 the country. To it also may be traced, as a primary 

 cause, the fumigation of nursery stock with hydrocyanic 

 acid gas now widely practiced by nurserymen. The 

 most frequent means of dissemination of the scale to new 

 localities is through the sale of infested trees. Also the San 

 Jose scale is largely responsible for the present nursery 

 and orchard inspection laws that have been enacted by 

 nearly every state in the Union and in the provinces of 

 Canada. 



Appearance, 



The appearance of the San Jose scale is too well known to 

 require any extended description. Briefly stated, the massed 

 effect of a large number on a branch or twig is that of a 

 grayish coating of a greasy, waxy substance, which when 

 scraped off in quantity appears to be more or less mixed 

 with very small yellowish specks. These specks are the 

 insects themselves, and the grayish waxy substance is made 



