374 PEAR GROWING IN CALIFORNIA. 



The larvae usually bore into small crotches, forming a characteristic 

 round-shaped burrow. Often injury is severe enough to cause the twigs 

 to break. This pest is usually more serious in the neighborhood of 

 brush piles, in which it hibernates and breeds. 



Control. 



Nothing in the way of a spray can be used effectively for this pest; 

 in fact it is not serious enough to make radical measures necessary. 

 Cleaning up of all brush piles, orchard prunings, etc. is the most import- 

 ant thing in connection with its control. 



BUR CLOVER OR COW PEA APHIS (Aphis medicaginis). 



Aphids are often exceedingly troublesome in the pear orchard and 

 because of the fact that they may spread the blight from tree to tree, 

 control becomes absolutely necessary in orchards where the blight is 

 present. This species is black in color, with distinct white markings on 

 the legs. It commonly feeds on leguminous plants, sweet clover, bur 

 clover, etc., attacking pear trees when there is a scarcity of its common 

 food plants. It feeds upon the tender growing tips of the pear twigs, 

 sometimes becoming exceedingly abundant. 



Control. 



Formula No. 3 may be used very successfully in the control of this 

 pest, as well as other aphids which affect the pear. 



CALIFORNIA PEAR SAWFLY (Gymnonychus californicus). 



In the pear orchards of the Central California Coast Region slight 

 damage is often done to the foliage of pears by a little green larva which 

 eats a characteristic circular-shaped hole in the leaves. Frequently 

 feeding begins on the margin, the larvae gradually eating back in the 

 manner shown in Fig. 166. The adult insect is a little shiny black 

 fly with yellow markings, one of many species of a family of insects 

 known as sawflies. 



Control. 



Use Formula No. 12. 



CHERRY OR CALICO SCALE (Lecanium cerasorum). 



In some of the counties surrounding the San Francisco Bay this 

 scale, which is an exceedingly large, showy, black and white species, is 

 common. 



Control. 



Control measures are not usually necessary, although when the pest 

 becomes abundant enough to be destructive either Formula No. 5, 

 6 or 7 may be used. 



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