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

Subject:  What Is this?
Geographic location of the bug:  Southern Illinois
Date: 07/15/2018
Time: 01:40 AM EDT
Your letter to the bugman:  Never seen this before in this area… what is this critter?
How you want your letter signed:  Curious

Hanging Thief

Dear Curious,
This is a predatory Robber Fly in the genus
Diogmites, commonly called a Hanging Thief because the insect often hangs from one leg while consuming prey.

What's That Bug? does not endorse extermination

Subject:  Hairy wasp-like bug with some kind of oral stinger
Geographic location of the bug:  Southeast Texas, USA
Date: 07/08/2018
Time: 10:51 AM EDT
Your letter to the bugman:  I’ve been seeing these guys at my work which is a fracking site in the middle of a cattle ranch. I have seen about 5 of them but all separately, not in a group. They look like giant wasps, but they’re very hairy and have some kind of stinger out of their mouths. I may have seen a stinger out of the thorax as well but I’m not sure. And I have noticed multiple dead bug carcasses around the area, such as grasshoppers and beetles. I thought it might be relevant in case these bugs are like the wasps who lay parasitic eggs in paralyzed bugs.
Picture taken in July.
How you want your letter signed:  Dave

Robber Fly:  Saropogon dispar

Dear Dave,
This is a predatory Robber Fly, and Robber Flies frequently capture large flying insects that they feed upon, so the carcasses you have found might have been prey.  Like other Flies, Robber Flies do not chew prey.  They feed on the fluids, leaving a dried carcass behind.  We are having trouble matching your images to an exact species or even a genus.  Its most obvious diagnostic features are its long legs, white beard, black wings and striped abdomen.  It really resembles a Hanging Thief in the genus
Diogmites, but they are usually orange.  We did locate a dark Hanging Thief on BugGuide, Diogmites platypterus, and it has a white beard and black wings, but your individual lacks the orange legs.  Our best guess at this time is the enormous Microstylum morosum, pictured on BugGuide, but they don’t have white stripes on the abdomen.  Does your individual have green eyes?  That is difficult to discern in your images.  Prolepsis tristis pictured on BugGuide also looks similar, but lacks the diagnostic white beard.  We have written to Eric Eaton for assistance.  For now, we are certain this is a predatory Robber Fly in the family Asilidae, and we hope to have a more specific identification for you soon.  Perhaps our readers will be able to assist.

Robber Fly:  Saropogon dispar

Thanks for the response! Yes the eyes were a dark green color. And it was very large, I approximate it to be 1.5-2 inches long. The Microstylum morosum looks like the closest match to me except for that abdomen and the bright green eyes. I didn’t know anything like this family of insects existed!

If it is indeed Microstylum morosum, it is the largest Robber Fly in North America.

Eric Eaton Responds
Ok, I submitted to the Facebook group, but then looked at the website for robber flies of Arkansas and may have found it:  Saropogon disparhttp://www.hr-rna.com/RNA/Main%20pages/Diogmites%20frame%20page.htm
Eric
author, Kaufman Field Guide to Insects of North America
http://bugeric.blogspot.com/

Thanks so much Eric.  We looked it up on BugGuide and Saropogon dispar sure does look correct.

What's That Bug? does not endorse extermination

Subject:  Flying insect
Geographic location of the bug:  massachusetts,  USA
Date: 07/13/2018
Time: 03:40 PM EDT
Your letter to the bugman:  Hi, there’s a bunch of these flying around. They seem to enjoy sitting in one place for a long time or sunbathing. Was having trouble identifying it.. But very curious about it.
How you want your letter signed:  Michal

Robber Fly

Dear Michal,
This is a beneficial, predatory Robber Fly and the ovipositor indicates she is female.  She uses her ovipositor to lay eggs and cannot sting with it.  Based on this BugGuide image, we are confident your Robber Fly is in  the genus
Efferia.

What's That Bug? does not endorse extermination

Subject:  Odd fly eating another fly
Geographic location of the bug:  Columbus Ohio
Date: 07/12/2018
Time: 05:07 PM EDT
Your letter to the bugman:  Found this cool guy on my trash bin with another smaller fly in its mouth. It also had a long stinger/appendage coming out of its bottom.  It was not afraid of me and simply wanted to finish its meal
How you want your letter signed:  Katy

Robber Fly eats Fly

Dear Katy,
The predator is a Robber Fly in the family Asilidae, but we are uncertain of the species.  Robber Flies are amazing predators that capture prey while flying.

What's That Bug? does not endorse extermination

Subject:  Possible Hymenoptera?
Geographic location of the bug:  Greene county, MO
Date: 07/11/2018
Time: 07:03 PM EDT
Your letter to the bugman:  My mom sent these pictures and I’m not sure what it is.
How you want your letter signed:  Jenny Parsons

Giant Robber Fly

Dear Jenny,
This is a Giant Robber Fly in the genus Promachus, possibly a Red Footed Cannibalfly, not a Hymenopteran.  Giant Robber Flies prey on large flying insects, frequently eating wasps and bees.

What's That Bug? does not endorse extermination

Subject:  Silver, winged insect with bristly legs
Geographic location of the bug:  Amesbury, MA
Date: 06/27/2018
Time: 10:42 PM EDT
Your letter to the bugman:  Hello! I love your site and thought this bug was fascinating as I’ve not yet seen it nor have a few folks I showed the picture to. The body appeared to be silver and black and the bristled legs each had a pincer at the end. The bug didn’t seem aggressive as I got close, but definitely had a tough appearance. Any ideas to what it could be?
How you want your letter signed:  AJ

Robber Fly

Dear AJ,
This is a beneficial, predatory Robber Fly, and based on this BugGuide image, it might be
Efferia aestuans or a closely related species.

What's That Bug? does not endorse extermination