NC State Extension Publications

Description and Biology

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Maple bladder gall mites, Vasates quadripedes, cause tiny wart-like growths on the tops of the leaves. Bladdergall mites are fascinating but microscopic eriophyid mites (mites that have only two pairs of legs). They overwinter on the bark of their host trees in a distinct overwintering form. In early spring as the new growth emerges, the overwintering mites crawl to the foliage and lay eggs from which hatch gall mites that feed on the expanding leaves and induce the host tissue to form galls inside of which the mites feed and reproduce. The offspring of the gall mites are overwintering forms that leave the galls and crawl to the bark to spend the winter.

Maple bladder galls

Maple bladder galls are pale green, then red, then brown to black.

Photo by J.R. Baker

Close up image of maple bladder galls on silver maple.

Maple bladder galls are well named!

Photo by J.R. Baker

Maple bladder gall opened to show hypertrophied cells and tiny maple bladder gall mites (arrows).

A maple bladder gall opened to show the mites inside.

Photo by J.R. Baker

Illustration of life cycle stages, egg, first nymph, second nymph, adult.

Eriophyid mites have only two nymphal stages.

Illustration by J.R. Baker

Host Plants

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Although the galls are alarming, they probably do no measureable harm to the tree. Maple bladdergall mites will not infest any other plant except maples, especially silver maple. One characteristic of gall mites is that they are exceedingly specific in their host plants.

Residential Recommendation

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If control is desired, eriophyid mites are susceptible to Sevin insecticide and to other pesticides labeled for "mites." The best time to treat is in late fall after maples have dropped their leaves. These mites are small enough that they can wedge into buds and other tight places so the treatment will have to be thorough for good control.


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For assistance with a specific problem, contact your local N.C. Cooperative Extension Center.

This Factsheet has not been peer reviewed.


Professor Emeritus
Entomology and Plant Pathology

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Publication date: May 16, 2014
Revised: March 23, 2024

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