Currently viewing the category: "Robber Flies"
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

Subject:  Insect
Geographic location of the bug:  Los Angeles backyard
Date: 09/10/2017
Time: 11:36 AM EDT
Hi! My grandson found this black bug–it’s about 1 1/2 ” long with a torpedo-shaped body with a narrow pointed end. The bug often elevated its rear end. He first found it on it’s back and saw it arch it’s back and move it’s legs over its body to flip onto it’s stomach. Not sure how many wings it has.
How you want your letter signed:  Brody

Giant Robber Fly

Dear Brody,
We believe this large predator is a Giant Robber Fly in the genus
Promachus, probably Promachus albifacies based on this BugGuide image.  It also resembles this unidentified species on the Natural History of Orange County site.

Thank you so much for your response!  My grandson (11) is thrilled to know the insect name and be on your terrific site.

What's That Bug? does not endorse extermination

Subject:  Is this a bee killer
Geographic location of the bug:  Hanover, Pennsylvania
Date: 09/04/2017
Time: 04:17 PM EDT
Is this a bee killer? If so should I be concerned?
How you want your letter signed:  Thanks you

Red Footed Cannibalfly

We believe your Robber Fly is a Red Footed Cannibalfly, Promachus rufipes.  Robber Flies in the genus Promachus are commonly called Giant Robber Flies or Bee Killers, according to BugGuide, so you are correct.  You should not be concerned.

What's That Bug? does not endorse extermination

Subject:  Bee Identification
Geographic location of the bug:  Spruce Pine NC
Date: 09/01/2017
Time: 04:28 PM EDT
Hi I saw this little critter on its back and was going to help flip him over but he turned back without my help. I thought he was just a regular Bee until I saw his wings legs and stinger. It’s the beginning of fall here I have to say I’ve never saw a bee quite like this!
How you want your letter signed:  SJ

Female Giant Robber Fly

Dear SJ,
This is not a bee.  It is a predatory Giant Robber Fly in the genus
Promachus, but we are not certain of the species.  What you have mistaken for a stinger is the ovipositor the female uses to lay eggs.  Here is a similar looking individual on BugGuide.

Female Giant Robber Fly

What's That Bug? does not endorse extermination

Subject: Impressive killer
Location: Roswell, Georgia
August 22, 2017 1:54 pm
I saw this flying around our yard yesterday, and dead in our driveway today. I believe it is the red-footed cannibal fly you mention on your page 3 of horse flies. Can you confirm this for me?
Signature: Maggie Bean

Giant Robber Fly

Dear Maggie Bean,
This is definitely a Giant Robber Fly in the genus
Promachus, but since its “feet” are hidden under its body, we cannot say for certain that it is a Red Footed Cannibalfly, but it is in the same genus which is well represented on BugGuide by many similar looking species.

What's That Bug? does not endorse extermination

Subject: Bug eating yellow jacket
Location: Just east of Toledo Ohio
August 18, 2017 2:07 pm
What’s this bug? Seen on a F150 killing a yellow jacket. Really big and interesting. Thank you
Signature: lilli

Red Footed Cannibalfly eats Yellowjacket

Dear Lilli,
This Giant Robber Fly in the genus
Promachus appears to be a Red Footed Cannibalfly.  Giant Robber Flies frequently prey upon large stinging insects like wasps and bees.

Wow tyvm. It was the most interesting bug I have seen in a very long time. Never seen it before is it rare?

Sightings on BugGuide cover about 1/4 of North America, and sightings generally occur from July to September.  We get numerous identification requests for Red Footed Cannibalflies each summer, so we don’t believe they are considered rare.

What's That Bug? does not endorse extermination