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

Subject:  Large Biting Fly
Geographic location of the bug:  Tyler, Texas
Date: 08/31/2019
Time: 12:08 PM EDT
Your letter to the bugman:  We see these ‘bugs’ usually in the fall. Their bite is painful and leaves whelps. Wasp killer spray does them in so we got pictures this time.
How you want your letter signed:  Bob & Elaine

Possibly Robber Fly

Dear Bob & Elaine,
Normally we would expect a large biting fly to be a Horse Fly or a Deer Fly, and this looks more to us like a predatory Robber Fly, but we have not had any luck matching your images to a species.  While we caution readers not to carelessly handle large Robber Flies as they might bite, we do not know of any reports of unprovoked bites from Robber Flies.  We will be sending your images to Eric Eaton to get a second opinion on its identity.

Possibly Robber Fly

Eric Eaton Responds.
Hi, Daniel:
Yes, it is a robber fly, but I suspect that it is guilty by association with something like a horse fly or deer fly.  Robber flies do NOT habitually bite people.  They are strictly predators of other insects.
Eric

What's That Bug? does not endorse extermination

Subject:  Is this a wasp?
Geographic location of the bug:  Vancouver area, British Columbia, Canada
Date: 08/26/2019
Time: 09:49 PM EDT
Your letter to the bugman:  I came across this aggressive little monster outside in late August near Vancouver. He was easily 2x the size of a honeybee, and while he preferred hanging out on the wooden bench, he made several short (1-2 second) flights before finding a new landing spot each time on the bench. He even had a mid-air tumble with a flying insect who dared to pass near him. He seemed quite aggressive and unpredictable, so sorry for the blurry pic! I couldn’t get too close.
How you want your letter signed:  Agatha

Bee-Like Robber Fly

Dear Agatha,
This is a Robber Fly, not a Wasp, and it appears to be
Laphria astur, based on this BugGuide image.  Large Robber Flies are aerial predators that take prey on the wing, and the “mid-air tumble” you witnessed might have been a failed attempt to capture a meal.

What's That Bug? does not endorse extermination

Subject:  What is this thing?
Geographic location of the bug:  North Carolina
Date: 08/15/2019
Time: 11:37 AM EDT
Your letter to the bugman:  Hello, recently I found this very strange looking…wasp? Hornet? I don’t know. It was dead when I found it. I tried searching for what it might be online but couldn’t find anything with a matching description. I hope you can help!! Thank you.
How you want your letter signed:  Mack

Robber Fly

Dear Mack,
This is a large, predatory Robber Fly in the family Asilidae, but we do not recognize the species.  The black coloration is quite unusual for an eastern species.  It might be
Proctacanthus nigriventris which is pictured on BugGuide.  Your dorsal, lateral and frontal views are excellent for an expert’s ability to identify the genus and species, but alas, we do not possess that expertise.  Perhaps one of our readers will provide a less general identification.

Robber Fly

Robber Fly

What's That Bug? does not endorse extermination

Subject:  New to my yard
Geographic location of the bug:  Southwestern PA, foothills of the Appalachians
Date: 08/14/2019
Time: 09:25 AM EDT
Your letter to the bugman:  I’ve just noticed these in my yard this year – and there’s quite a few of them.   Yesterday I saw one holding another smaller bug (gnat maybe?)in its, so I’m thinking they might be carnivorous.
How you want your letter signed:  Frankie

Gnat Ogre

Dear Frankie,
Your submission has us terribly amused.  We immediately suspected this to be a predatory Robber Fly in the family Asilidae, and we tried a web search for Robber Flies with huge eyes, and we quickly found some images posted to BugGuide indicating it might be in the genus
Holcocephala, but alas BugGuide is currently having technical difficulties and is not available, so we searched that genus name elsewhere and we encountered Discover Life where we learned members of this genus are commonly called Gnat Ogres, hence the source of our amusement.  For the sake of continuity, we are going to assume the prey you witnessed was in fact a Gnat.  The name Gnat Ogre is also used on iNaturalist.  According to iNaturalist, there are 40 species in the genus.

Gnat Ogre

Thank you! I love the name!!!

What's That Bug? does not endorse extermination

Subject:  Robber Fly
Geographic location of the bug:  Cleveland, NY 13042
Date: 08/08/2019
Time: 09:59 PM EDT
Your letter to the bugman:  Hi Mr. Bugman  – I came across this insect while photographing dragonflies in my small meadow of grasses and wildflowers. I heard him before I saw him. I was quite fascinated with how low and slow he flew and how loud he was! Sounded like a small drone! I noticed him first yesterday but all he did was fly back and forth without ever stopping. Then late this morning he was in the dirt on the edge of the little meadow acting like an ovipositing dragonfly, but in one place. Then this afternoon I saw him/her fly across the meadow and land quite close by. That is when I got the photos. Any ID help you can give me would be most appreciated.
How you want your letter signed:  Ginny

Hanging Thief eats Wasp

Dear Ginny,
This magnificent Robber Fly in the genus
Diogmites is a Hanging Thief, and it is eating its prey, a Wasp, in the typical manner which has led to its common name, by hanging from one leg.  We rarely try to identify Hanging Thieves to the species level as we don’t have the necessary expertise, but this sure looks to us like Diogmites discolor which is pictured on BugGuide.  You might have witnessed oviposition, because according to BugGuide:  “Oviposits in ground, and ovipositor equipped with spines to aid in covering eggs. Larvae are possibly predators in soil”

Hanging Thief eats Wasp

Dear Daniel,
Your incredibly fast reply is most appreciated! A Hanging Thief no less!! That was one of the things that fascinated me about this Robber Fly – in every photo she was hanging onto the vegetation by one leg. I really enjoyed all the information you provided. Our bugs never cease to amaze! Thank you so much for all of your help. Take care – Ginny
What's That Bug? does not endorse extermination

Subject:  Potential Carpenter Bee Robber Fly
Geographic location of the bug:  Austin, Texas 78757
Date: 08/06/2019
Time: 04:05 PM EDT
Your letter to the bugman:  I took pictures of two of these very large black bees/flies this morning. I noticed them when refilling a water saucer in a shady woodland setting. Is this a beneficial creature for my certified wildlife habitat, or should I be worried for wood damage in the area?
How you want your letter signed:  Curious Kat

Belzebul Bee-Eater

Dear Curious Kat,
This is definitely a predatory Robber Fly and not a Bee.  The white “cheeks” and yellow band on the abdomen are good indications this is a Belzebul Bee-Eater,
Mallophora leschenaulti, which is pictured on BugGuide.  According to BugGuide:  “has been reported to attack and kill hummingbirds” but we suspect that is a very rare occurrence.  In our opinion, though they are known to prey on Bees, the Belzebul Bee-Eater would be a beneficial creature in your certified wildlife habitat as it is a native species.

Belzebul Bee-Eater

What's That Bug? does not endorse extermination