Photo by Mary Holland.
Perched on a leaf, a robber fly (also called assassin fly) waits and watches for any movement in the air. The fly will abandon its perch to capture an insect as it flies past. Once it catches its prey, the robber fly quickly pierces the insect with its pointed proboscis to inject enzymes that will paralyze the insect and reduce its innards to a fluid that the fly then ingests. Robber flies hunt bees, beetles, dragonflies, grasshoppers, flies, and wasps. There are more than 6,000 species of robber flies worldwide; they can be identified by their stout proboscises, moustache-like facial bristles, and tapering abdomens. In the Northeast, they often hunt in dry, sunny fields during the hottest time of day.