12 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



Life History. — Very little 

 is known of the life history 

 of this mite. It apparently 

 passes the winter in the 

 bud scales, much as does the 

 pear-leaf blister-mite, and 

 begins to work upon the 

 leaves as soon as the buds 

 open in the spring. By the 

 middle of June it becomes 

 plentiful and often quite de- 

 structive, sometimes defoliat- 

 ing trees to quite an extent. 



Nature of Work. — In feed- 

 ing this mite chafes the under 

 epidermis of the leaf, causing 

 a rusty discoloration which is 

 v e r y characteristic. The 

 leaves are also curled by the 

 attacks of the mite. This 

 russeting is the only clue to 

 its existence in an orchard. 

 With a hand lens and some 

 pains they may be seen some- 

 times as tiny objects either 

 stationary or moving about 

 very slowly. 



Distribution. — This pest 

 was first discovered in California by Mr. Geo. P. Weldon, who took 

 specimens in San Diego, Sonoma and Contra Costa counties in 1913. 



Since then he has 

 found it in Modoc, 

 Yolo, San Joaquin 

 and Fresno counties 

 and the writer has 

 received it from San 

 Luis Obispo County, 

 thus indicating its 

 very general distri- 

 bution throughout 

 the State. 



Food Plants. -The 

 pear appears to be 

 the preferred host 

 of this mite, though 

 the peach and occa- 

 sionally the apple 



big. 13. — I lie pear-leaf rust mite, Epitrimrrus pyriNalepa. ,," i , 



Ventral and dorsal views. (After Nalepa from Parrott) <l r( ' attacked. 



Control.— Control measures are the same as for the pear-leaf 

 blister-mite. 



Fig. 12. — Pear leaf showing- discolored 

 edges produced by the pear-leaf rust mite, 

 Epitrimerus pyri Nalepa. Slightly enlarged, 

 (Original ) 



