564 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



examined with a compound microscope to distinguish the species. 

 One is shown much magnified in Fig. 500. They are elongate, 

 with two pairs of legs, and slender abdomens, composed of 50 

 to 80 small rings, frequently marked with rows of small tubercles 

 and ornamented with a few hairs and bristles. 



Life History. The mites spend the winter in the buds, and 

 as warm weather approaches in the spring they become active 

 and move toward the base of the growing bud scales and feed 

 there. As the young leaves unfold the mites migrate to them. 

 They burrow through the surface of the leaf and feed upon the 

 succulent tissue within, setting up an irritation which soon results 

 in reddish spots on the surface. Within these mines the eggs 

 are laid, as many as 14 having been found in a single blister. 

 The young hatch in about a week and burrow around in all 



FIG. 500. The pear leaf blister-mite (Eriophyes pyri Pgst.) : highly magni- 

 fied. (After Parrott.) 



directions, feeding on the tissues and juices. When full grown 

 they leave the gall through small openings in the under surface 

 and start new colonies which produce similar galls. They con- 

 tinue to reproduce and migrate throughout the summer, and under 

 favorable conditions become numerous enough to completely 

 infest the new leaves as they appear. In the fall they leave the 

 leaves to hibernate in the buds as already described. 



On pear the blisters are at first greenish pimples, which become 

 reddish and later brilliant red blisters, and finally they become 

 brown or black and the tissue corky. When numerous the 

 galls coalesce,' forming dark brown patches over the leaf, which 

 often break open, particularly along the edges of the leaves. 

 On the blossom ends of the fruit and on the stems they produce 

 light-colored pimples, which do not seem to injure the fruit. 

 On apple the blisters are less brilliantly colored than on pear, 



