PEAR AND QUINCE INSECTS 227 



experience of other growers indicate that such heavy appHca- 

 tions of kainit on clay soils is very liable to injure the trees. 

 In such cases recourse must be had to repeated, thorough, 

 shallow cultivation during June and July. By this means a 

 large nunibtM- of the larva? and pupa^ will be d(^stroyed. 



References 



Riley, Rept. U. S. Com. Agr., pp. 283-289. 1885. 

 N. J. Agr. Exp. Sta. Bull. 99. 1894. 

 Marchal, Ann. Hoe. Ent. Fr., pp. 5-27. 1907. 



The Pear-leaf Blister-mite 

 Eriophyes pyri Pagenstecher 



The leaves of pears and apples are often disfigured by reddish 

 or greenish-yellow blisters which later in the season turn brown 

 (Fig. 206). These blisters are caused by colonies of minute, 

 whitish, elongate, four-legged mites, ^^^ inch in length, living 

 within the tissue of the leaf (Fig. 207). These creatures are 

 not insects, but belong to the class of animals known as Arachnida, 

 to which belong spiders and scorpions. While originally a 

 native of Europe, it has now become widely distributed and 

 occurs wherever the pear is cultivated. About 1902 it suddenly 

 became an important apple pest in the Eastern states and 

 Canada. The cause of this remarkable change of habit is 

 unknown. 



The adult mites pass the winter snugly hidden away beneath 

 the second or third bud scales. With the bursting of the buds 

 they migrate to the tender leaves and burrow beneath the epi- 

 dermis of the under surface. The irritation thus caused pro- 

 duces a thickening of the leaf tissue and results in the formation 

 of a blister-like gall. The minute, whitish eggs are deposited 

 within the gall, and the young remain there until mature. They 

 then leave the gall through a minute opening on the under side, 



