Maple bladdergall mite

Distribution

Canada

Micro-habitat(s)

Leaf

Damage, symptoms and biology

The maple bladder gall mite causes the formation of a mushroom-shaped gall. The green or pinkish-red galls appear on the upper surface of the leaf and, if numerous, may cause the blade to bend.

This mite, which has several generations per year, overwinters as an adult on the trunk or branches. The female feeds on the swelling buds, causing them to produce a mass of excess cells (gall) that enclose the invader.

The females lay eggs inside the gall, and newly hatched larvae feed on the gall tissue and complete their development. The adults exit the gall through a hairy opening on the underside of the leaf in search of an overwintering site. They may also produce additional galls if the leaf tissue is favourable to their development. The maple gall bladder mite is believed to overwinter as an adult.

Life cycle (East of the Rockies)

Other information

The presence of this mite, which is native to Canada, was first reported in the late 1930s. Local infestations have occurred every year since then in Quebec and Ontario. The mite’s geographic range covers all of Eastern Canada and several States in the Eastern United States.

Populations vary from one year to the next, and may even become on the verge of disappearing. Althoug a large number of galls frequently form on the foliage, the maple bladdergall mite is not considered harmful and control methods are not required.

Main host(s)

Red maple, silver maple, sugar maple