270 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



THE CONTROL OF THE PERNICIOUS OR SAN JOSE SCALE 



(Aspidiotus perniciosus Comst.) 

 By E. O. EssiG 



An address delivered at the Convention of the Northwest Inspectors' Association, 

 Spokane, Washington, November 15, 1912 



The destructiveness of the Pernicious or San Jose Scale has been so 

 great and its distribution so rapid throughout this country that it has 

 received more real scientific investigation than has been accorded to 

 any other common pest, excepting perhaps the codling moth, and it 

 is doubtful if even this latter should be made an exception. Indeed, 

 so much has been done in every state to devise new and efficient means 

 of control that I wonder why this subject should have been allotted 

 to me for presentation before such a body as this. Perhaps it is be- 

 cause so much has been written and so little is ever presented in a 

 personal way that much of the real practical information is lost. 

 Climatic conditions so change the modes of operation in controlling 

 this pest that we find certain specialized S3'stems which vary with the 

 different localities. In view of these special conditions I shall attempt 

 to include only those lines of procedure which may be used by all. 

 In fact I believe that the only available suggestions which I can give 

 will resolve themselves into recommendations for the proper application 

 of spraying methods. 



The control of all insect pests has usually been directed along purely 

 artificial lines, such as the applications of powders and sprays, and the 

 use of certain gases. In many of the states no other methods have 

 been thought of or attempted. But in justice to all parties, we should 

 recognize here at least two important controlling factors — artificial 

 and natural. The former include spraying, fumigation, etc., and the 

 latter, the importation, establishment and distribution of natural 

 enemies. 



Artificial Control. Among the methods artificially used in 

 controlling this pest, spraying is recognized as most efficient in pro- 

 portion to the cost involved. No doubt fumigation would be more 

 thorough and lasting, but the outlay for equipment, chemicals and the 

 tremendous wear upon the tents, makes this method impracticable. 

 We may also safely say that lime-sulphur is the accepted insecticide. 

 Originally salt was added to make it more severe, which proved as 

 destructive to the trees as to the scale, and like all other detrimental 

 ingredients was left out as soon as this fact was definitely established. 



Looking squarelj^ at the problem of the control of this scale at the 



