Utah State University Extension
The poplar bud gall mite belongs to the eriophyid mite family. These mites are microscopic and about one-fourth the size of a spider mite. Adults are about 0.2 mm in length, reddish in color, and spindle-shaped.
Roe, Alan H., "Poplar Bud Gall Mite" (2002). All Current Publications. Paper 1362.