How to Manage Pests

Pests in Gardens and Landscapes

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 at green tip stage

Mites attack leaves through the bloom stage
Mites attack leaves through the bloom stage


Statewide IPM Program, Agriculture and Natural Resources, University of California
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