8 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



made along the sides of the midribs of the leaves, while the base and 

 margins of the apple leaves are preferred. It is not uncommon to find 

 the entire surface of the leaves of both the pear and apple entirely 

 covered with the galls. 



Distribution. — This is a very common mite throughout the pear- 

 growing districts of the State. It is very abundant in the interior 

 valleys and the fruit districts of the Sierra foothills. 



Food Plants. — The pear and apple are seriously attacked, the mites 

 working upon the leaves, stems of the leaves and fruit, and also upon 

 the fruit. The other plants recorded as hosts are European mountain 

 ash, shadbnsh and the cotoneaster. 



Control. — The control of this mite is becoming quite an important 

 factor in the raising of pears, especially in the Sierra foothills in 

 Placer, Nevada and El Dorado counties. Many of the sulphur prepa- 

 rations, as pure flowers of sulphur, flowers of sulphur and hydrated 

 lime, lime-sulphur and atomic or milled sulphur have been used. The 

 commercial lime-sulphur (1-13) has given very good results. Atomic 



Fig. 8. — Buds of peai' tree in good condition to spray for the pear-leaf 

 blister-mite, Eriophyes pyri (Pgst. ). Natural size. (Original) 



sulphur has not been thoroughly tried out, but judging from its effi- 

 ciency in controlling other mites it is also suitable for this one. The 

 most important consideration is the time of application, which should 

 be made in February, just as the buds are opening, as shown in Fig. 8. 

 At this time the hibernating adults are moving to the young leaves to 

 lay eggs, and a spraying at that time will kill nearly all of them. 

 Mr. J. E. Hassler, Horticultural Commissioner, fully demonstrated 

 this in El Dorado County in the spring of 1914, and it has also proven 

 reliable in other places. 



