Rhopalomyia californica Felt

Baccharis pilularis

Flower bud or leaf gall, single or clustered, lobulate, greenish or reddish-brown, diameter 1/4 to 3/4 inch, midge, summer

Rhopalomyia sp. [Unclear how this differs from R californica]

Lobulate bud gall, midge, summer

Rhopalomyia californica
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This midge induces polythalamous terminal bud galls on both the erect and prostrate forms of coyote brush [Baccharis pilularis]. The galls are round to lobed with lumpy protrusions across the surface.

Rhopalomyia californica Felt

This species forms lobed, succulent, usually leafy bud galls (Fig. 3) on B. pilularis in California. It was imported into Australia as a potential biocontrol agent of B. halimifolia in 1969 and 1982. The gall midge took hold only after the 1982 introduction and since then has effectively established itself in Queensland and New South Wales (McFadyen 1985, Julien 1992, Palmer et al. 1993). It was also introduced into Texas in 1985 to control B. halimifolia and B. neglecta. Typical galls were observed on B. neglecta at Belton, Texas in 1986, but none was subsequently found (Boldt, unpub. data). The ecology of this species and its parasites has been investigated by Ehler (1982, 1987, 1992) and Ehler and Kinsey (1990, 1991, 1993). This species is very similar to Rhopalomyia sulcata Gagne. Differentiation between the two species is made under R. sulcata.

[Gagne here considers Rhopalomyia baccharis a junior synonym of R californica but this synonymy was later reversed]

Rhopalomyia californica

Hosts: Baccharis pilularis

bud gall, usually Terminal, lobed and succulent

This species is multivoltine. Eggs are laid in terminal growth, and the hatching larvae crawl between bud scales where the buds begin to form.

Similar galls occur on B glutinosa in Oklahoma, but it is not known whether R californica is responsible for that gall also.

Range: CA, OR