Canyon flies are significant pests of humans and animals in coastal mountain and foothill habitats of the southwestern United States. The canyon fly group is comprised of seven related fly species within the Fannia benjamini complex: F. benjamini, F. conspicua, F. thelaziae, F. tescorum, F. operta, F. neotomaria, and F. arizonensis. The geographic range of each of these fly species is unknown, though some overlap in range among species is recognized at a few locations where they have been studied. All flies in this group are attracted to animals to feed on body secretions such as tears, mucus, sweat, saliva, or blood from open wounds. Their persistent attempts to land upon the face and body of the host can result in considerable nuisance.

     Canyon flies are diurnally active, with host-seeking generally greatest soon after sunrise and in the hours before sunset. Where daytime temperatures are high, a pronounced lull in fly activity will be noted during midday. Little is known about the variation in activity among the canyon fly species, but those species that have been examined in California show a distinct seasonal activity with adult fly abundance peaking during late spring and early summer or in early-mid fall.