Robber Fly – Laphria index
Family Asilidae – Robber Flies
Live adult flies photographed at Winfield, Illinois. Size: 18 mm. Prey = Polydrusus weevil.
The metallic golden pubescence on this fly’s thorax and abdomen is really quite stunning when viewed close-up. The fly is in the process of sucking out the liquified guts of an unfortunate Polydrusus weevil, also commonly known as the “green immigrant.” The American midwest is experiencing a population explosion of these weevils in the summer of 2005, and the robber flies are having a field day with them.
Because of their predatory habit of feeding on other insects and their voracious appetites, they contribute to the maintenance of the natural balance among insect populations. To some extent, parasitic wasps and flies are taken by them, but much of their prey consists of plant-feeding insects.
Reference: Bugguide.net Robber Fly – Laphria index
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