The infestation caused by this mite is most noticeable as
shiny, convex swellings on the upper surface of the leaf blade
and on the underside as patches of shallow, large, solitary
concavities lined with felty, yellowish hairs, among which the
mites are to be found. These patches have well-defined edges
and lie to the side of the midrib between the lateral veins; the
erineum growths miss the small secondary veins and appear as
thickened partitions. The erineum is particularly characteristic
in that each structure is covered with short, minute, unicellu-
lar hairs. Although erineum patches are fewer
on the leaves, they are easily recognized because of their size
and color.

[photo pg. 115]

- Hartford Keifer,Edward Baker,Tokuwo Kono,Mercedes Delfinado,William Styer: (1982) An Illustrated Guide to Plant Abnormalities Caused by Eriophyid Mites in North America^©