crimson erineum mite

At only one tenth the width of a human hair in length, a crimson erineum mite (Aceria elongata) is barely visible to the human eye unaided by magnification. Its claws, dorsal shield markings, and other identifying body features are not. Identification in the field is possible only by noting the properties of the abnormal growths (galls) it produces on its host.

When an individual leaf cell is injured by a mite, it produces a small, nipple-like projection (papilla) on the upper surface of the leaf. The papilla has a rounded tip, visible only with magnification, and is filled with colored fluid. As the mite feeds on adjacent cells, the aggregation of papillae forms a pustule-like, felty patch (erineum). The erinea are usually scattered over the leaf surface, thickest toward the upper (apical) half, and avoiding the major veins. They are greenish-white at first, soon becoming crimson or purplish. They reach their maximum extent, and are most noticeable, in summer.

The infestation is sometimes abundant and can cause leaf distortion and premature leaf drop.

Total length: 0059″ to .0085″ (150 to 216 microns)

Sugar maple and possibly also black maple

Galls visible from early spring to fall

The life cycle of the crimson erineum mite involves alternating generations and is adapted to seasonal changes in the host. Overwintering females emerge in early spring from bark where they spent the winter. The migrate to newly developing buds and ride out on new leaf growth. They begin feeding, enter the resulting galls, lay eggs, and die. In late spring and early summer the eggs in the galls hatch, producing white male and female mites (protogynes). In mid-summer, red female mites (deutogynes) are produced. They fill the galls, obscuring the white protogynes. In September, these female deutogynes migrate to bark crevices in stems and twigs, where they will spend the winter.

The infestation can cause leaf distortion and premature leaf drop when abundant.

Sources

7, 30, 82.

Common in Eastern North America

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.