Posts Tagged ‘Asilidae’

When I first encountered two insects this past weekend at Huntley Meadows Park, I thought they were mating. Looking a little closer, I realized it was a robber fly and its prey, which, after some research, I conclude is probably a Striped Horse Fly (Tabanus lineola). In addition to its unusual eyes, check out the sharp mouth parts of the horse fly that are used, I believe, for biting. Ouch!

There is a whole family of robber flies, known as Asilidae, of varying sizes and shapes, including the Red-footed Cannibalfly that I have featured several times recently. This robber fly was considerably smaller than a Red-footed Cannibalfly, but has many of the same general characteristics. They both grasp their prey with their long legs and inject it with saliva that paralyzes the victim. The saliva eventually liquifies the insides of the prey and the robber fly sucks out the liquified material through its proboscis. I think that the robber fly in the photo was in the middle of that process when I spotted it.

Robber Fly

© Michael Q. Powell. All rights reserved


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As I was getting ready to leave my local marshland park on Friday, I spotted what I thought was a small dragonfly. Upon closer examination, it turned out to be a robber fly, subduing a captured prey.

There are a lot of varieties of robber flies in the Asilidae family and I am not sure which kind this is, but robber flies have a reputation for being really vicious predators.

Wikipedia describes their hunting method in these words, “The fly attacks its prey by stabbing it with its short, strong proboscis injecting the victim with saliva containing neurotoxic and proteolytic enzymes which very rapidly paralyze the victim and soon digest the insides; the fly then sucks the liquefied material through the proboscis.”

I guess we can all be thankful that robber flies are not big enough to hunt humans—except perhaps in science fiction movies.


© Michael Q. Powell. All rights reserved.

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My eyes were so attuned to dragonflies yesterday that my first thought when I stumbled upon this insect perched at the top of a plant was that it was a tiny dragonfly. The pose especially looked familiar.

The more I looked at it, however, the more I realized that the legs and winds were all wrong and the head, which in this profile shot looks a bit like a dragonfly’s, was really different. From another angle it sort of looked like a fly, but not any fly that I had ever seen. What is it?

I think that what I have here is a robber fly (from the insect family Asilidae). So far I have not been able to get any more precise in identifying this guy’s species. The description of robber flies in Wikipedia, however, is pretty. scarey.

“The short, strong proboscis is used to stab and inject victims with saliva containing neurotoxic and proteolytic enzymes which paralyze and digest the insides; the fly then sucks the liquefied meal through the proboscis.”

Yikes! That description alone is enough to bring back flashbacks of alien movies and zombie thrillers.

I may not sleep well tonight.

© Michael Q. Powell. All rights reserved.

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