About Euhexomyza schineri (Giraud, 1861)
Euhexomyza schineri produces smooth, circular galls that form as swellings integrating into the stem from new twigs below the bud. Gall formation begins in summer, with growth continuing through autumn. The gall overwinters holding multiple yellow-green larvae before pupation. Pupation takes place in late winter to early spring, after which adult flies emerge and drop to the ground. After and during the departure of pupae from the gall, Cytospora canker can develop around the gall, triggered by wounds from exiting pupae or birds trying to feed on the gall. Adult Euhexomyza schineri flies are roughly 2–4 mm long, with stout, shiny, dark bodies. When active, they rest on leaves during the day. Quaking aspen (Populus tremuloides) is the main documented host of this species, though it has also been recorded from many other poplar species. This species has primarily been recorded across the West Coast and Northeast of the United States, and Southeastern Canada. Individual occurrences have also been reported in Europe and Asia.
