The multi-chambered galls are induced in apical and lateral buds. They are first apparent in mid May, when they form about 1 cm-wide globular swellings in shoot tips. ... Some galls occur in clusters around the shoot tip or in adjacent lateral buds... At this point, several leaves surround a small spongy mass at the base of the gall, which grows gradually over the next month up to a final size of 6 cm in diameter. ... The leaves that are tightly wrapped around the spongy mass are much wider than the normal, thin leaves of the plant ... Around the second week of June, these leaves begin to loosen, revealing the whitish tissue in which 5–35 larval chambers are embedded. Adults emerge from late June to mid July, at which point the fleshy core of the gall is exposed. ... Soon after the gall midges emerged, the fleshy tissue turns black, and dry galls remain on the plants for several weeks.

Galls are mono- or polythalamous and light green...Adults emerge in September so probably overwinter in a gall in the crown of the plant. Host: E. graminifolia.