"The gall midge Dasineura epilobii (Löw), a flower gall maker on fireweed, Chamaenerion angustifolium (L.) Scop. (Onagraceae), and other closely related plants, is shown to be a Holarctic species on the basis of anatomical and molecular evidence." Oviposition occurs at the tip of unopened buds. Galls appear as swollen, unopened flower buds. D. epilobii exhibit multiple generations in a season with the last overwintering in the soil.

[Dasineura] epilobii. Widespread Europe, Russia (western Siberia), USA (Alaska, Washington) Canada (British Columbia, Quebec). Epilobium angustifolium; E. latifolium, E. hirsutum (Onagraceae).

Russo 2021 states that these polythalamous galls are swollen and aborted flower buds measuring 7mm long to 4-6mm in diameter. Russo 2021 goes on to state that larvae exit the galls in fall and overwinter in soil.

opened gall with young (because colourless) larvae ... a single galled flower ...

[click below for photos and list of references]

Abstract: "The gall midge Dasineura epilobii (Löw), a flower gall maker on fireweed, Chamaenerion angustifolium (L.) Scop. (Onagraceae), and other closely related plants, is shown to be a Holarctic species on the basis of anatomical and molecular evidence. The cecidomyiid is redescribed and appears to differ from other congeners by the dearth of microtrichia on the dorsum of the gonostylus and their absence from the apicoventral surface of the gonocoxal lobe."