Ontonagon Co., MI Canon 250D (+4) close-up lens

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Robber Flies

Robber Fly (2008-07-12 12-27-14)

Order Diptera : Infraorder Asilomorpha : Family Asilidae

The flies belonging to the family Asilidae are known as robber flies or assassin flies. There are over 7,000 species worldwide. Although they are nasty-looking creatures, they feed on other insects making them helpful to humans.

The robber fly in the photo, species unknown, was photographed by me in Ontonagon County in Upper Peninsula Michigan. It was taken using a Panasonic DMC-FZ50 camera with a Canon 250D (+4 diopter) multi-element close-up lens. No post-processing was done.


The legs are stout and covered with spines. They have three simple eyes (ocelli) on the top of the head between two large compound eyes. There are bristles on their face which looks like a moustache. The antennae have three segments.

They prey on bees and wasps, grasshoppers, dragonflies and other robber flies. Basically, if it’s the right size, they will eat it. Some species are more delicate and focus on smaller prey.


Life Cycle

Robber flies go through complex metamorphosis beaning they start out as eggs, then caterpillar-like larva, then pupae and lastly adult.

Photo © 2008 Gary J. Sibio. All rights reserved.

Text © 2017 Gary J. Sibio. All rights reserved.


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Written by Gary J Sibio