INJURIOUS INSECTS, FUNGOUS DISEASES, ETC. 179 



larvae or the adults will not hurt the eggs or the insects in 

 cocoons. 



The best way to control the pest is to wash the trunks of 

 infested sugar maples with a solution of whale-oil soap at 

 the rate of one pound to four gallons of water, or oil emul- 

 sion at weekly intervals from the middle of July until the 

 leaves fall in late autumn. In early November, after the foli- 

 age is all gone, the trunks should be given a final treatment 

 with the whale-oil soap or oil emulsion to kill the tiny larvae 

 that remain all winter. In that way the brood can be killed. 



San Jose Scale {Aspidiotus perniciosus Comst.). Al- 

 though this species has been most destructive of fruit-trees, 

 it attacks a large number of shade and ornamental trees as 

 well. The twigs of badly infested trees, instead of being 

 smooth and shiny, are covered with dark gray, scurfy 

 patches that have a peculiar granular look which any one 

 familiar with the bark of a rapidly growing tree will imme- 

 diately recognize as not a normal condition. 



The winter of the insect is passed in the half grown con- 

 dition, covered by a round black scale about the size of a 

 pin's head. During that season the insects do not feed and 

 there is no drain upon the vitality of the tree. In May they 

 resume growth. About the middle of June the young larvae 

 are born and begin to crawl from beneath the female in- 

 sects. These young are minute, active, yellow atoms that 

 crawl outwardly to the leaves and the young shoots. They 

 insert their slender mouth-filaments into the plant tissue and 

 begin to suck the sap. They change in form, become more 

 circular, and very soon waxy filaments begin to ooze out all 

 over the body, which form the scale. In about five or six 

 weeks the species is mature, reproducing in turn, and by 

 the end of the season the broods are no longer distinct, all 



