Currently viewing the category: "Robber Flies"
What's That Bug? does not endorse extermination

Subject:  robber fly identification
Geographic location of the bug:  New Jersey
Date: 02/04/2018
Time: 01:18 PM EDT
Your letter to the bugman:  Greetings:
I’m having trouble identifying Robber Flies. I’ve uploaded 2 fairly similar pictures (more pictures can be found at https://www.inaturalist.org/observations/4028726 and https://www.inaturalist.org/observations/4142315 respectively). The first has been IDed as a  Promachus hinei and the other as a Red-footed Cannibalfly (Promachus rufipes). Are these IDs correct and these are different species? If so, what’s a good way to distinguish them? And are there any other similar Robber Flies I’m likely to run into in New Jersey?
P.S. I think Robber Flies are interesting, but don’t really know much about them except that they’re considered fairly tough predators in the arthropod world.
How you want your letter signed:  Baffled By Robberflies

Red Footed Cannibalfly

Dear Baffled,
Sometimes it is not possible to identify a species conclusively from a photograph alone, and the Giant Robber Flies in the genus
Promachus can be a challenge.  We are somewhat inclined to doubt the accuracy of the individual identified as Promachus hinei on iNaturalist because BugGuide lists the range of the species as being considerably west of New Jersey with Ohio being the easternmost sighting.  Because of the proximity of your two sightings in both location and time, we would be most inclined to suppose them to be the same species, and the Red Footed Cannibalfly is a likely possibility, especially since both of your individuals have red “feet” and the physical description on Encyclopedia of Life states:  “Adults are 28 – 35 mm long. Typical of robberflies, the eyes are large and separated by a deep trough on top of the head. The body is covered in yellow bristles, particularly on the head and abdomen. The legs are black, except for orange tibia and pulvilli. As with other members of the genus Promachus, this species has sharp claws and an abdomen that extends beyond their folded wings. ”  We apologize for not being able to provide a conclusive identification and we suspect that if actual specimens were to be identified by a dipterist specializing in Robber Flies, many of the individuals identified on our site as Red Footed Cannibalflies might actually be members of a similar looking species in the same genus.  Like many other large Robber Flies, Red Footed Cannibalflies and other members of the genus are able to take large prey, often stinging wasps and bees, on the wing.  Thank you for becoming a Patreon member and helping to support the free service we are able to supply on the World Wide Web.

Red Footed Cannibalfly

Greetings:
Thanks for telling me what you know about these guys. I suspect that I’m going to have this problem with a lot of insects; too many similar-looking relatives. (I was kind of hoping you’d be able to tell me that no other species that looks like the Red-footed Cannibalfly lives in NJ.)
John
Hi again John,
We located this comment on BugGuide “As I understand it, there are three ‘tiger-striped’ species of 
Promachus in the eastern U.S., with P. hinei being the most common in the central U.S. It is distinguished from the more southern P. rufipes by the reddish rather than black femora and from the more northern P. vertebratus by the larger dark areas dorsally on the abdominal segments and distinctly contrasting two-toned legs.”  That supports our supposition that both of your individuals are Red Footed Cannibalflies, Promachus rufipes.
Greetings Daniel:
That was helpful. Just for due diligence, I then checked out BugGuide’s info on Promachus vertebratus to see if that could be a good candidate for my Robber Flies. And it really isn’t; P. vertebratus’s range is typically outside NJ, and it’s green or red eyes aren’t a match for any of my Robber Flies.

I’m cautiously optimistic that the Red-footed Cannibalfly is what I’m seeing.

Thanks again.

John

And we agree, so we are changing the subject line of the posting to reflect that.

What's That Bug? does not endorse extermination

Subject:  Horsefly or Drone?
Geographic location of the bug:  Chile central
Date: 01/06/2018
Time: 06:14 AM EDT
Your letter to the bugman:  This little fellow was spotted on a tree. Ive never seen this kind before in this region, we have gray horse flies and Scapia Lata in the south.  Seeing it from distance it looked like a queen bee or drone (because of the size), a “bumblebee male” someone suggested, but I believe is a smartly bee-colored horsefly. Can you identify the bug ?
How you want your letter signed:  Mr.

Robber Fly

Dear Mr.,
This is one impressive looking female, predatory Robber Fly in the family Asilidae.  We were unable to locate any Chilean individuals that resemble your submission, but it does remind us of the North American Bee Killers.  Large Robber Flies like this one often take large winged prey, including wasps and bees, on the wing.

Thank you very much!!! Your identification has been confirmed by a local entomologist, this specimen corresponds to Obelophorus landbecki species, apparently a stealthy hunter from the arid Chilean central zone.

Thanks so much for writing back with a species identification.  We did locate an image on the Pierre.Comte.Over blog as well as an image on Insectos de Chile, and in both instances they are images of mounted specimens.  We could not find any images online of living specimens, which makes the posting of your contribution to our site unique.

What's That Bug? does not endorse extermination

Subject:  identify flying insect
Geographic location of the bug:  cape town, south africa
Date: 01/04/2018
Time: 03:05 AM EDT
Is this a wasp or is it a non-stinging insect?
How you want your letter signed:  APPLE COHEN

Robber Fly

Dear Apple,
This is not a Wasp and it is a non-stinging insect.  This is a predatory Robber Fly in the family Asilidae, and it reminds us of the North American genus known as the Hanging Thieves because after catching winged prey, including stinging wasps and bees, the Hanging Thief feeds by sucking vital fluids from the prey while hanging from a single leg.  Flies bite, they do not sting.  While we believe there is little chance of a person being bitten by a Robber Fly in most situations, attempting to handle a Robber Fly might result in a bite.

What's That Bug? does not endorse extermination

Subject:  Bee Fly?  Laphria thoracica?
Geographic location of the bug:  Carlsbad, NM
Date: 11/16/2017
Time: 10:40 PM EDT
This guy (or gal) was hanging out on our screen door in early August of this year.  He didn’t seem to mind when we went in or out, and he didn’t mind being photographed.  Eventually, he flew away.  He looked like a bee crossed with a big fly.  We don’t recall seeing such a colorful one before.  We searched your site and a few others on the internet.  We think he looks like some of the Laphria Thoracica on Bug Guide but not exactly.  We were hoping you might know.  Thanks for all the time and hard work you put into your site.
How you want your letter signed:  Curious

Bee Killer

Dear Curious,
This is a Robber Fly, not a Bee Fly, and you do not have the genus correct.  It is NOT
Laphria thoracica, as that species has a yellow thorax based on BugGuide images, and your individual has a black thorax.  In our opinion, this is a member of a different genus of Robber Flies.  We believe it is a Bee Killer, Mallophora fautrix, a species pictured on BugGuide can be distinguished from the previous genus and described on BugGuide as “Large, fuzzy, bee-mimicking robber flies. Resemble Laphria, another genus of robbers that mimic bumblebees, but is even hairier and has antennae with a very thin terminal final segment, whereas Laphria has thick antennae.”

What's That Bug? does not endorse extermination

Subject:  Weird insect : cross between cicada and spider
Geographic location of the bug:  Sydney
Date: 10/11/2017
Time: 06:15 PM EDT
We found this in our backyard. Could you help me identify this insect? And if it is harmful to my kids?
How you want your letter signed:  Dida

Robber Fly

Dear Dida,
This is a predatory Robber Fly in the family Asilidae, and members of the family are not aggressive toward humans, however, we would not try to handle one at the risk of being bitten.  Your individual looks similar to this individual posted to Australian Geographic.

Hi Daniel,
Thanks for your quick respond! 🙂 we are new to Australia, and constantly see ‘new’ insect species. As Australia is known for venomous animal kingdom, we try to keep our kids from harm. Thanks again!
Cheers!
Dida

What's That Bug? does not endorse extermination

Subject:  Cross between a wasp and dragonfly
Geographic location of the bug:  Maryland
Date: 09/12/2017
Time: 12:02 AM EDT
Any ideas? Some are calling this a cicada killer but those look MUCH more like wasps…this has a more dragonfly like tail but appears to only have two wings..
How you want your letter signed —
Chris in Md

Giant Robber Fly

Dear Chris,
This is a predatory Robber Fly, and you were astute to observe that it has a single pair of wings.  We believe it is a Giant Robber Fly in the genus
Promachus which is well represented on BugGuide.

What's That Bug? does not endorse extermination