The galls were found by R.J. Gagné in capitula, carried on a pedicel among normal capitula but shorter and hidden by them. The gall is conical-cylindrical, smooth, white to green, or sometimes red, and apically tapering. Each gall contains a single larva. A galled capitulum is wider and harder to the touch than capitula without galls.
”- Netta Dorchin, Miles V. McEvoy, Todd A. Dowling, Warren G. Abrahamson, Joseph G. Moore: (2009) Revision of the goldenrod-galling Rhopalomyia species (Diptera: Cecidomyiidae) in North America©