Globular midrib swelling
Galls are especially visible from below. This is the species responsible for the damage. Larvae are gregarious. When full grown they leave the gall through a dorsal longitudinal slit.
Hosts: S. betulifolia, S. latifolia, S. salicifolia, S. tomentosa
Distr: New England to Ontario and British Columbia to Oregon
- Raymond J. Gagne: (1989) The plant-feeding gall midges of North America©