Ash Flower Gall Mite

Eriophyes fraxiniflora

HOST Ash

DAMAGE/SYMPTOMS Damage is caused by a small, microscopic mite called an eriophyid mite. The mite distorts the male flowers of the ash. These galls are originally a greenish-yellow color but dry out and turn brown.

LIFE CYCLE Female mites overwinter under bud scales and protected areas. In the spring, females actively feed and lay eggs on the buds. The male flowers disfigure and form gall-like tissue where the mites continue to develop. The mites leave these galls later in the summer and move to bud scales to overwinter.

MANAGEMENT The pests are generally secondary and infest stressed trees. The galls rarely affect the health of the tree. Due to the protection of the mites within the galls, insecticide treatments are often minimally effective in controlling mite densities and often kill beneficial natural enemies of the mites. Larger trees are difficult to treat effectively. If chemical controls become necessary, a contact insecticide or miticide labeled for the host can be applied when the first blossoms appear. Also, a dormant oil can be applied prior to bud break.

A Ash flower gall mite early-season distortion. B Ash flower gall mite distortion during summer. C Late-season galls.