boxelder pouchgall mite

Boxelder pouchgall mite is 7 ⁄1000″ (180 microns) long, about as long as a human hair is wide, and 21 ⁄10000″ (55 microns) wide. The human eye cannot see particles smaller than 50 to 60 microns, so this mite is probably invisible to most people. It is most easily identified by the type of growth (gall) it produces and the plant species on which it is found.

Boxelder pouchgall mite is found exclusively on boxelder (Acer negundo). In the spring, the mite forms a hollow, dull tan or gray pocket on the under surface of the leaf. The pocket is covered with a mass of felty whitish hairs. On the upper surface, it appears as an irregular, blister-like bump. The galls are solitary, though there are usually many galls on a single leaf.

Total length: 7 ⁄1000″ (180 microns)

This is the only mite that causes bladder galls on boxelder leaves.

Boxelder

Spring through fall

Sources

24, 29, 30, 82, 83.

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.