INSECTS AND DISEASES 



and sulphur to destroy them by smothering or 

 choking the spray must be applied on the dor- 

 mant wood In the spring or fall or both. Thor- 

 oughness is most essential. 



7. l^iiE Oyster Shell Scale, although It 

 IS essentially the same in Its habits and In its 

 methods of sucking the sap from the tree is 

 not as bad a pest as the San Jose scale because 

 it is less prolific, there being but one brood a 

 year. Still this scale often destroys a branch 

 and sometimes a whole tree. The " lice " win- 

 ter as eggs under the scale and hatch in late 

 May or early June. After crawling about the 

 bark for two or three days, the young fix their 

 beaks into it and remain fastened there for life, 

 sucking out the sap. By the end of the season 

 they have matured and secreted a scaly cover- 

 ing under which their eggs for the next season's 

 crop winter. A smothering spray like lime and 

 sulphur applied strong when the trees are dor- 

 mant will practically control this scale. But 

 the young may be destroyed in summer by a 

 contact spray such as tobacco leaf extract or 

 whale oil soap. 



8. The Leaf Blister Mite Is a small, four- 

 legged animal, so small as hardly to be visible 

 to the naked eye. It passes the winter in the 



lOI 



