Black Bee Fly, Thyridanthrax atratus, female.

A largish, all black bee fly that does not show its proboscis like most other bombyliids. It is nest-
parasitic on Sand Wasps -- females collect sand grains for bombing runs on the wasps' burrows; they
also fly around with the wasps, occasionally getting chased by the females (not the males -- they're
too lazy), but always eluding them, which is interesting because the female wasps, in turn, are voracious
predators of another, smaller, bee fly which they hunt and capture in the surrounding woodlands.