A small, green to pink-red, hairless, globular to capsule-shaped gall on the upper side of leaves of Populus tremuloides. Only a small flat surface, not protruding at all, is visible on the lower side. Observed from Alaska to Prince Edward Island and south to New Mexico, fresh specimens reported between May and August.

This gall closely resembles the gall induced by Harmandiola globuli, known from Populus alba and tremula in Europe.

This gall morphotype can be distinguished from other midge galls on Populus leaves by the following traits:

• Larva concealed within galled tissue, protruding only on the upper side of the leaf
• Thin walled, capsule shaped, small