Saturday, August 11, 2012

Robber Fly Pestered by Flies

I’ve been seeing Robber Flies of all sizes, but my favorites are the big guys.  It’s enjoyable to watch something that is easy to approach and view without the use of any special optics.  These are ambush type predators that perch near an open area and fly out to capture insect prey as it flies by.  They always put on a good show.

I found this Promachus hinei busily consuming a large stink bug.  The Robber Fly inserts its mouth parts into its prey and then injects a calming toxin along with digestive chemicals.  The liquefied tissues are then ingested.

I’ve seen Robber Flies capture some rather large prey items.  The stink bug isn’t necessarily large, but it’s a heavy insect that probably took all of the Robber Fly’s strength to haul over to this leaf.

A swarm of small flies was taking advantage of this opportunity for a meal.  I’ve never before seen this type of behavior.  The flies arrived in a hurry, but I don’t know if they were attracted by the Robber Fly or the stink bug. 

Some of the little flies were using the Robber Fly as a perch.  The Robber Fly periodically raised its abdomen and kicked its legs to dislodge the little pests.  The scene reminded me of flies at a picnic.

The Robber Fly eventually completed its meal and dropped the bug carcass to the ground.  I found it interesting that none of the little flies followed the bug.  The bug only fell a few feet and if it was what originally attracted the flies, they should have been able to find it in its new location.  Maybe the pack followed the Robber Fly to take advantage of its next meal.  I’ll definitely be watching for these little flies on future Robber Fly kills.

A Camera Critters submission.


  1. Cool shots of the fly. Awesome captures.

  2. Beautiful macro pictures of a fly.
    Hanne Bente

  3. Those are kleptoparasitic flies. Different ones are attracted to chemical signals from different prey. Stingbugs often attract flies from the family Chloropidae. I'll often see them attracted to spider kills.

  4. that was a fascinating collection of crystal clear pix! Never heard of a robber fly, let alone seen one.....I have heard of stink bugs, but this is the first time seeing one, even if its just a carcass, and a pretty colored corpse it makes! thanx

  5. Thanks Eileen.

    Thanks Hanne.

    Thanks Judy.

    Thanks Pat.

    Thanks for the information, Troy. I'll be more watchful for these flies in the future.

    Thanks Joanne. The large Robber Flies make a loud buzz when they fly. A lot of people miss seeing them because they are trying to get away from the buzz.

  6. Looks wicked!

    Catching up with Camera Critters. Here's my
    Critter post, come and see.