638 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



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 



FIG. 494. Old leaf cluster with galls of pear leaf blister-mite on apple fruit 

 and leaves. (After Parrott, Hodgkiss and Schoene.) 



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, w r hich do not seem to injure the fruit. 

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



