plum finger gall mite

Eriophyid mites (Eriophyes spp.) are so small that they are almost impossible to see with the naked eye. Unless a scanning electron microscope is available, a morphological description of an adult individual is useless. The mite is most easily identified by the shape of the gall it produces and the plant species on which it is found. An infestation may be unsightly, but the damage caused by this mite is merely cosmetic. The plant is not significantly harmed.

Plum finger gall mite is a specialized plant feeder. In Minnesota it can be found on American plum, chokecherry, and European plum. In other areas it also infests bitter cherry, Klamath plum, and wild goose plum.

The pouch-type finger galls appear on the upper side of a leaf. They are solitary, though there are usually many galls on a single leaf. They are randomly scattered on the surface of the leaf blade.

The galls are variable in length, thicker at the tip than at the base (club shaped), and erect or leaning at an angle to the leaf surface. They are green to yellowish at first, often reddish near the base, eventually turning brown.

Tiny, almost microscopic

This is the only species that causes finger galls on the hosts listed below. It is not found on other plant species, and other mite species do not produce finger galls on these plants..

American plum, chokecherry, European plum, bitter cherry, Klamath plum, and wild goose plum

One generation per year. The first galls develop April to July.

The female overwinters in a crevice of a bud near the base of a branch. It emerges in the spring and seeks a newly developing leaf. As it feeds on the leaf, a chemical in its saliva causes the leaf cell to expand, forming a pouch. It then enters the pouch, lays 50 to 60 eggs, and dies. In late spring the eggs hatch, producing males and females that remain in the pouch throughout the summer.

Another eriophyid mite, Eriophyes prunidemissae, is normally found on the same branch. It overwinters in the buds at the tip and near the tip of the branch. It has two generations per year. The second generation invades the galls of the chokecherry finger gall mite. At the end of the season, when the gall splits open and releases the mites, Eriophyes prunidemissae outnumbers the chokecherry finger gall mite.

In Minnesota, leaves of American plum, chokecherry, and European plum.

Sources

7, 24, 27, 29, 30, 82, 83.

Common

Order
The family Eriophyidae was formerly classified within the order Trombidiformes, specifically in the suborder Prostigmata. However, molecular phylogenetic analyses, beginning in the early 2010s, have strongly challenged this placement. Current research indicates that Eriophyidae represents a very ancient and basal lineage within the order Acariformes. While Acariformes was historically treated as a superorder by some classifications, it is now widely recognized as one of the two major orders of mites (along with Parasitiformes). Due to ongoing debates about their precise relationships with other mite groups, Eriophyidae is currently placed directly under Acariformes without being assigned to a specific suborder.

Luciearl
5/28/2025

Location: Fairview Twp.

Luciearl
5/24/2025

Location: Cass County

Location: Charlottetown, Prince Edward Island, Canada

Mark Hager
7/2/2021

Location: 21 miles north of Grand Rapids.

Location: Duluth

prolific infestation on one of five trees

Location: Walker, MN - near Chippewa Nat Forest

We just discovered them today!

Location: Chokecherry bush in my back yard, Hopkins, MN

the bush appears to be covered with these galls.