Robber fly with prey

Asilidae

Robber fly · Arverne Preserve · 20 June 2026

A robber fly on the open sandy ground at Arverne with what is left of a meal. Robber flies are hunters of sunny open ground everywhere, and the white band near the tip of the abdomen, in front of a dark, swollen end, marks a male Efferia, one of the commonest genera on exactly this kind of coastal sand.

They hunt other insects on the wing, dropping onto prey from a perch and stabbing it with a short, heavy proboscis that both kills and liquefies from the inside. The bristled face and the sunken groove between the eyes, arranged to shield them from a struggling meal, are family features shared across the whole group; the species within the genus is not something a photograph settles.