125 Records

"These Goldenrod (Solidago sp.) leaf galls are caused by a fly (Cecidomyiidae: Asteromyia carbonifera). These flies also carry a symbiotic fungus (Botryosphaeria dothidea = Sclerotium asteris) with them. The Gall Midges disperse the fungus and the fungus aids in keeping away parasitoids that would attack the developing Gall Midge larvae. In the [top] photo the lower two inserts are the same old gall. The one on the right has had the surface peeled back to expose the black fungus underneath. This wearing off of the upper surface would occur naturally - but I was not that patient so I used my knife to speed the process. When one observes 'tar-spots' on the leaves of Golden Rod it is all that is left of the gall – only the black fungus remains." (R. Orr, pers. comm.)

Forms green to purplish leaf blisters in Conyza, Erigeron, Grindelia, and Solidago (BugGuide).