WSU Extension

Hortsense

Oak : Jumping oak gall
(revision date: 6/24/2015)


Biology
Jumping oak galls cause small yellow spots on the upper surface of infested leaves. On the underside of the leaves are tiny seedlike galls. These appear in mid-summer or later. Inside each gall is the larvae of a tiny wasp. In the fall, the galls drop from the leaves to the ground, where the activity of the larva causes the gall to jump an inch or more off the ground. The wasps overwinter in the galls on the ground. In the spring, females lay eggs in opening oak buds. The larvae cause blister-like galls, deforming the leaves. Adult females emerging from these galls lay eggs on the leaves, producing larvae which cause the jumping oak galls. Although they may be unsightly, jumping oak galls do relatively little damage. Some yellowing and premature leaf drop may occur.
Management Options

Non-Chemical Management
  • On small trees, it may be possible to hand-pick affected leaves to improve the tree's appearance.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images
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Caption: Jumping oak galls
Photo by: A.L. Antonelli