Two adults emerged within 2 weeks after galls were collected May 9, 1989 at Site 6.

This monothalamous gall develops from the upper surface of a persistent leaf. The coloration and pubescence of the gall surface is similar to that of the unaffected leaf. At maturity it is prune-shaped. Internally, a central cavity is lined with sclerenchyma. Only two galls, both occurring on the same leaf, were found during this study. They were 4 mm in height and 2 and 3 mm respectively in diameter.

Gall on leaves...
Gall sessile...
Gall convex at apex...
Gall ovoid, widest at midlength, wrinkled...Rhopalomyia rugosa Gagné

Galls are 4 mm long by 2–3 mm wide. These were found only once, in spring on persistent leaves...Host: A. tridentata