Gall Midge - Asteromyia carbonifera
Females lay eggs on the underside of goldenrod leaves (Solidago sp.). The development from egg to adult takes 4-5 weeks, and there are several generations per year.
The galls are flat and circular. They contain a symbiotic fungus, Botryosphaeria dothidea, which the larvae does not eat. The fungus confers some protection against parasitoid wasps. The females carry spores of the fungus.
Habitat: On goldenrod