The known distribution of V. californica includes the western third of the U.S. as mapped by Foote et al. (1993), who also noted that it had been collected in Baja California Norte. Its known hosts are Chrysothamnus nauseosus (Novak et al. 1967, Wasbauer 1972, Wangberg 1978, Foote et al. 1993) and C. parryi (Gray) Greene (Wangberg 1978), a high-altitude species in southern California (Munz 1974) which we have not examined for the presence of V. californica.
The larvae develop in short, subsurface mines mostly formed basally in current season's branches, and are not easily detected on infested plants. They cause limited swellings, not readily detectable galls.
However, unlike A. thoracica and contrary to Wangberg (1978), we could not bring ourselves to call the feeding sites of V. californica "galls." Instead, like Foote et al. (1993), we prefer the description, slight "swelling," or better yet, as Dodson (1987b) described the "gall" of V. dodsoni Foote "a rather inconspicuous swelling" of a branch, because this is the only external sign of the larva or puparium within (Fig. 5A, B, C, D, E).
Masked by normal variations in thickness of uninfested branches and stems of C nauseosus at our study site, and by the conspicuous galls caused by other insects, e.g. Aciurina trixa Curran (Wangberg 1981, Dodson and George 1986, Dodson 1987b) and several species of Cecidomyiidae (Gagne 1989), the slight swellings symptomatic of V. californica are, indeed, "inconspicuous."

Valentibulla californica
Elliptical-stem-gall Tephritid

These stem-colored galls may taper gently or expand abruptly and may be symmetrical or lopsided.