238 Peach-Growing 



A single female may produce 300 to 400 young, and as 

 there are several generations each year, depending on the 

 length of the growing season, the progeny of one insect may 

 become almost inconceivably large. 



The primary injury is caused by the insects sucking the 

 juices from the host plant ; but the punctures in the bark 

 made by the beaks of the vast number of the insects which 

 sometimes occur evidently poison the tissues, as indicated 

 by the inner bark showing a reddish discoloration, thus 

 still further effecting serious and speedy injury. 



Though the younger limbs are especially affected, every 

 part of a peach tree above ground on which the bark has 

 not become roughened with age may become incrusted with 

 the scales. Not infrequently on young trees the infestations 

 may even extend somewhat below the surface of the ground. 



Methods of control of San Jose scale. 



While many different substances have been and still 

 are being used in spraying for this insect, the standard 

 remedy in most regions has come to be a concentrated lime- 

 sulfur mixture, either home-made or commercially pre- 

 pared. Directions for making and using this mixture are 

 given on pages 279-282. 



Other preparations include kerosene emulsion, various 

 petroleum oils, miscible oils, and a considerable number of 

 proprietary preparations put out under trade names. 



The principal spray applications have to be made 

 during the dormant season, since the spray must come in 

 contact with every insect in order to kill it, and because of 

 the practical impossibility of making the applications with 

 sufficient thoroughness to be effective when the trees are 

 in full leaf. Besides, an insecticide that is strong enough 



