No. 4.] FRUIT TREES AND INSECT FOES. 119 



finally covers completely, but it spreads to the fruit, where it 

 produces unsightly red spots, so injuring its appearance as to 

 greatly reduce its value for sale. 



This scale is now generally present in Massachusetts, and 

 is rapidly becoming more abundant. 



It is one of the most prolific insects known, the descendants 

 of a single individual under favorable conditions having been 

 calculated as numbering more than three billions in a single 

 season; and as all of these obtain their food from the sap of 

 the tree, it is not uncommon to see good-sized trees completely 

 dried up as the result of their presence. They can be destroyed 

 only by sprays which come in actual contact with their bodies, 

 and strong enough to penetrate the armor which covers them ; 

 and sprays which can do this are not safe to use on the trees 



Fig. 3. — Oyster-shell scale: a, underside of female scale, showing 

 eggs ; b, upper side of same, both much enlarged ; c, female 

 scales on a branch, natural size; d, male scale, much enlarged; 

 e, male scales on branch, natural size. The fine lines to the 

 right of a, b and d show the real length of the scales. 



except during the winter months, while the 'trees are not 

 growing. Yet a fruit raiser who understands the proper meth- 



