First Description of The Stem Gall of Rhopalomyia baccharis Felt, 1908 (Diptera: Cecidmyiidae), on Baccharis pilularis De Candolle (Asteraceae)

The gall of Rhopalomyia baccharis Felt, 1908, previously known only as a “stem gall” on Baccharis pilularis De Candolle is described for the first time. Adults of the gall inducer are indistinguishable from those of the related Rhopalomyia californica Felt, 1908, but the pupae are distinctive. The latter species makes a distinct terminal bud gall on the same host. Distinguishing pupal characters and galls are illustrated. The biology of R. baccharis is outlined.