Seasonal development
and life cycle—Pearleaf blister mites
Pearleaf blister mites overwinter as adults beneath bud scales of both fruit and leaf buds. The terminal
bud of a twig generally carries the heaviest population. Blister mites can reproduce during winter, and
all growth stages are found under bud scales. When buds start to grow in spring, the mites attack emerging
leaves from green tip through bloom stage, and developing fruit.
Eggs are laid in the blisters, and young mites feed on tissue within the protection of the blister.
Eggs are spherical and pearly white. Young mites move in and out of the blister through a small hole
in its
raised center. At maturity they leave the blister and move to new locations to start new blisters.
Blister mites pass through several generations on leaves, but their activity slows during warm summer
months. Fresh blisters often are produced in fall on flushes of new leaf growth. Before leaf fall,
the mites leave the blisters and migrate to buds for winter. | 
Mites
attack at green tip stage
Mites
attack leaves through the bloom stage
|
