Hanging thieves

Photographed in situ [1]

An awl robberfly (Neoitamus cf. flavofemoratus) catches a small deer fly (Tabanidae). Some robber flies exhibit striking mimicry of bumblebees and spider wasps with fuzzy hairs, yellow bodies, or bright orange wings, but others like this species are less charismatic. It’s possible that the orange legs on Neoitamus may likewise be mimicking the appearance of stinging wasps (e.g. Auplopus mellipes, Polistes metricus).. or on the other hand, it might be an aposematic signal to bird predators of their piercing bite.

Focus stack of three images; photographed after pursuit [3]

Hanging thieves (Diogmites spp.) are some of the most attractive of the robber fly family. Many are bright orange with chrome green eyes, standing tall at rest as if on stilts. In most robber flies the legs are long and powerful, equipped with hooked tarsi for latching on to aerial prey. Diogmites is no exception, and I was alerted to this predation event from the loud buzzing on the ground after the two took a tumble. Initially the hanging thief dragged the parasitic fly (Tachinidae) into the shade to subdue its victim more discreetly. Repetitive jabs through the underside with its sharp beak and neurotoxic enzymes, and the prey was soon rendered immobile. As I approached the hanging thief began to seek higher ground, grasping leaves and branches with its front legs while the hind four manipulated the prey item. This behavior is what gives Diogmites its common name. Often times they can be found hanging from vegetation while having a snack, rocking back and forth in the wind like they are on a swing set.


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