This species and barbata are indistinguishable, but their galls are distinctly different. Both are squat leaf galls with a rugose, hairless patch at the base.
That of villosa is covered for almost its entire length with long hair (Fig. lb), while that of barbata is covered for only slightly more than half its length with short hair.
- Raymond J. Gagne, GL Waring: (1990) The Asphondylia (Cecidomyiidae, Diptera) Of Creosote BushΒ©