316 Report oF THE DEPARTMENT OF ENTOMOLOGY OF THE 
appear as corky spots of a reddish brown color, which to the touch 
are very distinct from the healthy portions of the leaf. ‘The indi- 
vidual galls average from one-twelfth to one-eighth of an inch in 
diameter and are usually oval or quadrangular in shape. Leading — 
to the interior of each affected area there is usually one or more tiny 
openings. Often the spots coalesce, forming irregular dead areas, 
with a smooth or slightly raised surface and of a dark brown color, 
which rupture the leaf at the margins. Severe infestation seems to 
destroy the fresh color and gloss of the leaves and may cause them 
to be much wrinkled or to curve over, exhibiting the under surfaces. 
About July 1 the most striking effects of the mites upon the 
leaves appear, especially if there is much yellowing of the foliage, 
as frequently occurs. Upon the upper. surfaces of such leaves the 
mite-infested spots are of a light brown or of a dark green color 
and are uniformly brown beneath. These spots are thickly massed, | 
forming a dark, broad band of irregular. width along each side of 
the leaf which contrasts conspicuously with the intervening lght 
yellow area about the main rib. To one standing on the ground 
and viewing the leaves from beneath, this striping of the leaves 
is very suggestive of variegated foliage of certain ornamental plants. 
The mites also injure the fruits and the fruit stems. As a result 
of the attacks by the mites the young fruit soon after setting pre- 
sents light green pimples, about one-eighth of an inch in diameter 
which stand out in marked contrast with the darker colored surface 
of the apple. These swellings are usually irregularly grouped about 
the calyx cavity. Apples that are half grown may show light, blister- 
like areas of one-quarter of an inch in diameter, suggestive of pock 
marks, which are variously distributed upon the surface, usually 
about the calyx cavity. These markings would ordinarily pass 
unnoticed and seem in no way to affect the value of the fruit. 
Injured apple stems show somewhat similar pimples of a smaller 
size. Severe infestation produces much thickened stems, which 
present a very irregular outline. In several instances the work of 
the mites upon the leaves and fruit stems of the same cluster has so 
weakened the stems as to cause the falling of the fruit. Premature 
dropping of the apples by this means seems to be of rare occurrence 
and even on the worst infested trees is not sufficient to appreciably 
affect crop production, 
