PEAR GROWING IN CALIFORNIA. 



FIG. 166. Larvae and characteristic injury of California 

 pear sawfly, Gymnonychus californicus. 



COTTONY CUSHION OR FLUTED SCALE (Icerya purchasi). 



To the writer's knowledge this species has never been found injuring 

 pear trees except in that part of the Central California Coast Region 

 included in Santa Clara County. In certain orchards there it has 

 become exceedingly destructive particularly on Winter Nelis, and is con- 

 sidered by the pear growers to be one of the most serious pests of this 

 fruit. It attacks the smaller twigs, devitalizing them, and, as is char- 

 acteristic of all scale insects, the trees are covered with a sticky honey- 

 dew. This same pest occurs generally in citrus orchards but is there 

 controlled by its natural enemy, Vedalia cardinalis. It is interesting to 

 note that in the case of the pear the Vedalia can not long exist because of 

 heavy spraying with arsenate of lead for the control of codling moth. 

 This material, while it has no effect upon the cottony cushion scale, does 

 poison the ladybirds, consequently the scale has a chance to develop. 



Control. 



Much experimental work has been done in the Santa Clara Valley by 

 the county horticultural commissioner in an effort to determine effective 

 methods of control. Thus far nothing has been discovered that is 

 altogether satisfactory. More or less good can be accomplished by the 

 use of oil sprays, Formulae Nos. 5, 6 and 7. 



EUROPEAN FRUIT LECANIUM (Lecanium corni). 



This Lecanium is of quite common occurrence on pear trees, and but 

 for the presence of the little parasite, Comys fusca, it would become very 



157 



