368 



ECONOMIC ENTOMOLOGY 



stage, and the small round red eggs can be readily recognized in the 

 crotches of fruit trees. There are several generations in a season. In 

 autumn it sometimes invades houses. 



Family Eriophyid^ (Blister Mites) 



(Consult Bull. 283, N. Y. Ag. Exp. St.) 



Pear-leaf Blister Mites {Eriophyes pyri Pgst.). — This introduced 

 mite is responsible for the reddish or yellowish blisters on the leaves 



Fig. 242. — Pear-leaf blister mite {Eriophyes pyri). (After Nalepa and Parrotl ) 



of pear and apple. These blisters turn brown later in the season, 

 and badly infested leaves drop. Nursery stock is often badly injured. 

 The mites live in colonies beneath the epidermis, forming blister- 

 like galls. Within these galls the minute oval white translucent eggs 

 are laid and hatched, and the young mites grow to maturity. They 

 then leave by a minute opening on the lower surface and go to new 



