The spring-generation galls occur in early to mid May in young Solidago gigantea sprouts and are located close to the ground.

First instar larvae that have overwintered in the rhizomes form the early galls The galls are composed of many short and narrow leaves, with 1-8 white, conical chambers containing a single orange larva each.

The summer galls contain 6-20 white, conical chambers, and larvae of R. capitata are heavily attacked by parasitoids.

Some shoot tips can support larvae of both species at the same time, resulting in galls with morphological attributes of both species, and ectoparasitoids are found feeding on the larvae and pupae of the gall inducer.

This article related to members of the fly infraorder Bibionomorpha is a stub.