Cecidomyiidae

Rhopalomyia

Artemisia tridentata

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Rhopalomyia hirtibulla

This small monothalamous gall (Fig. 12) occurs singly or in small to large confluent groups. The galls are densely clothed with long trichomes giving them a white fuzzy appearance. The mature gall is approximately 1 mm in diameter and of equal height. Emergence of the adult from a central larval chamber results in a small circular hole (Fig. 23) at the top of the gall. 

Developing gall were first observed on July 19, 1968 at Site 15. They are similar in appearance to the mature galls. Growth was completed between that date and the end of March of the following year. Old galls remain on the plant until the persistent leaf series is shed. 

Biology and taxonomy of the Rhopalomyia Gall Midges (Diptera: Cecidomyiidae) of Artemisia tridentata Nuttall (Compositae) in Idaho

Rhopalomyia hirtibulla
Bead Gall Midge

This gall midge induces small, hairy, monothalamous, round to slightly conical bead-like galls on leaves of Great Basin sagebrush.

Plant Galls of the Western United States