Deformed flower head, about 10mm long and 5-6 mm wide, covered by enlarge bracts that are smooth and reddish to yellowish outwardly, covered in white hair on inner side.

Cockerell (1904) described it as a deformed flower head, about 10 mm long by 5. 6 mm broad and covered by the greatly enlarged involucral bracts, which are outwardly smooth, reddish to yellowish, and inwardly covered with white trichomes. The host was given only as "Artemisia sp." Inasmuch as Rhopalomyia sp. appear to have narrow host preferences, future identification of R. coloradella should be difficult.

Deformed flower heads, length 10 mm, diameter 5-6 mm. On undetermined Artemisia.

Galls in deformed flower heads.