Adults emerged September 10-17, 1968 from galls collected on September 9 at Site 14. On the collection date the host plants were in early bloom.

This polythalamous rosette gall (Fig. 32) grows from a bud on the current year's stem and is subtended prior to maturity by two or more ephemeral leaves. It is composed of several whorls of mostly equal, linear to acicular leaves surrounding two to four sclerenchymatous larval capsules.

The basal diameter of one measured gall was 6 mm. Its outer leaves were up to 10 mm in length and the other leaves approximately 5 mm in length.

- Robert G. Jones, Raymond J. Gagné, William F. Barr: (1983) Biology and taxonomy of the Rhopalomyia Gall Midges (Diptera: Cecidomyiidae) of Artemisia tridentata Nuttall (Compositae) in Idaho^©