Currently viewing the category: "Robber Flies"
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Subject: Strange, perhaps injured, bug
Location: White Marsh, MD
August 8, 2014 7:21 pm
This insect has been hanging around our patio — first seen sitting on a concrete block under a set of wooden steps that lead down to our patio, then the next morning, on the patio itself, about 2 feel from first location — and it has me stymied. About 2 1/2 long, large black eyes, yellow and black stripes. Doesn’t move when approached, or react to loud noises. What the heck is this?
Signature: Thanks, Joan G

Red Footed Cannibalfly

Red Footed Cannibalfly

Dear Joan,
This predatory Robber Fly looks like a Red Footed Cannibalfly,
Promachus rufipes, and we believe it is probably perfectly fine and behaving like the stealth predator that it is.  Like many predators, Red Footed Cannibalflies are territorial, and when the hunting is good, they will remain in the area.  Large Robber Flies are among the few predators that will attempt to prey upon stinging wasps, and perhaps there is a nearby nest of hornets or paper wasps that is supplying this individual with a ready source of food.  Robber Flies take prey on the wing, and when a likely source of food flies by, we predict this individual will take off and snatch an unsuspecting wasp or other insect out of the air.  Robber Flies are not aggressive toward humans, but we would caution you to refrain from trying to catch one with your hands as that might result in a bite, though we have never received a report of a person being bitten by a Robber Fly.

Thank you so much!  My granddaughter will be thrilled to learn this, and I am relieved to know about it’s peaceful character.  Yes, there are wasps about – I’m happy to have him here!
Joan Garrity
Serenity, courage, wisdom.

What's That Bug? does not endorse extermination

Subject: It’s an ALIEN INSECT!
Location: Indianapolis indiana
August 8, 2014 3:13 pm
What in the HAIL is this insect? It was on my sweet corn. We live in Indiana. Thank you!
Signature: Bugs,

Hanging Thief

Hanging Thief

There is nothing alien about this magnificent, predatory Robber Fly in the genus Diogmites, commonly called a Hanging Thief.  It is a native genus.  This individual appears to be waiting to ambush some large flying prey, often bees or wasps.  The common name Hanging Thief is derived from the manner in which the predator hangs from a single leg while feeding on its captured prey. 

OMG! How COOL! Haha thank you. It was really terrifying because it would turn it’s head to look in my direction when I would talk.
I am a collector of praying mantids. And it was really interesting to me that this insect was able to turn his head like that. I thought I read somewhere that only praying mantids were capable of doing this. Do you know what I’m talking about? Thank you so so much! Very cool insect to have around in my garden!
Thanks again!

Today was quite the day for large Robber Flies.  We have four new postings, including another Hanging Thief and two Red Footed Cannibalflies.

Haha. How funny!
So what is it called when an insect can move it’s head/neck joint around like this one and praying mantids do?

Hmmm.  Flexible perhaps?  According to National Geographic on mantids:  “They have triangular heads poised on a long ‘neck,’ or elongated thorax. Mantids can turn their heads 180 degrees to scan their surroundings with two large compound eyes and three other simple eyes located between them.”  No special adjective is used to describe the flexibility.  According to Featured Creatures:  “Robber flies are opportunistic predators, their diets often reflecting prey availability in a particular habitat. Shelly (1986) reported that of the nine Neotropical Asilidae species he studied, diet constituents were more than 85% composed of insects from the orders Diptera, Coleoptera, Hymenoptera, Homoptera, and Lepidoptera. Furthermore, larger species tended to consume a greater diversity of prey taxa. Robber flies generally establish a perching zone in which to locate potential prey. Perching height varies by species, but generally occurs in open, sunny locations. Asilidae seize their prey in flight and inject their victims with saliva containing neurotoxic and proteolytic enzymes. This injection, inflicted by their modified mouthparts (hypotharynx), rapidly immobilizes prey and digests bodily contents. The robber fly soon has access to a liquid meal, which is generally consumed upon returning to a perched position.”  No mention is made of head rotation.  We had better luck on the Asilidae Homepage Information on Robber Flies Morphology where multiple experts are quoted.  According to Lehr (1988): “Head flattened, transversely rounded or slightly oblong, mobile” and according to Majer (1997):  “Head is relatively short and broad with more or less convex occiput, freely moveable.”  To there you have it.  According to the experts, the head is either “mobile” or “freely moveable.”  P.S.  We also just posted an image of mating Red Footed Cannibalflies which brings to total Robber Fly postings today to five.

What's That Bug? does not endorse extermination

Subject: what kind of bug is this?
Location: Newark, DE in the United States
August 5, 2014 11:46 am
My kids have been telling me about this crazy looking bug that has been eating bees in our back yard. But I have never seen one personally until today my son pointed one out with a bee captured in its mouth while both are captured in a spider Web! If you could identify this so I can explain to them I would greatly appreciate it alot. Plus for my knowledge also. Thank you greatly and Good bless.
Signature: Pyle Boys

Spider eats Hanging Thief eats Yellowjacket

Spider eats Hanging Thief eats Yellowjacket

Dear Pyle Boys,
We need to begin by telling you we love your documentation of a multi-link Food Chain.  We only wish your image was sharp enough and detailed enough for us to be able to identify the Spider.  The flying predator is a type of Robber Fly known as a Hanging Thief in the genus
Diogmites.  The Hanging Thief gets its common name because it often hangs from one leg while eating the large winged prey, often bees or wasps, that it captures on the wing.  The prey in question is not a bee, but a Yellowjacket.

Multi-Link Food Chair:  Spider eats Fly eats Wasp

Multi-Link Food Chair: Spider eats Fly eats Wasp

I am gonna attach a few more pics of the spider close up and hopefully this can help. And thank you for clearing up the curiosity for me and my sons! And glad you like the food chain effect my son thought it was cool how life works. Thanks again!

Possibly Common House Spider

Possibly Common House Spider

Thanks for sending the additional images, but unfortunately, the images are not critically sharp and it also appears that the color is decidedly cyan/blue, which makes the subtle coloration on the spider difficult to distinguish.  The Hanging Thief and Yellowjacket were quite obvious, but not so with the spider, which may be a Common House Spider, Parasteatoda tepidariorum.  You can see the resemblance to this individual on Bugguide.

 

What's That Bug? does not endorse extermination

Subject: Strange big eyed bee eating bug
Location: Bellflower, Ca
August 4, 2014 10:43 am
Hello Bugman,
Monday, August 4, 2014. My daughter saw this strange bug on our tomato cage. When I went to take its picture, I saw that it had a bee in its legs. The bee was upside down and looked dead. We think it was eating the bee.
This bug had what looked like brown wings and huge eyes. Please help identify this strange big eyed bee eating bug.
Thank you
Signature: Deana Campbell

Robber Fly eats Bee

Robber Fly eats Bee

Hi Deana,
This is some species of Robber Fly in the family Asilidae, but there is not enough detail in the image to make a more specific identification, but we suspect it is a Bee Killer,
Mallophora fautrix.

Thank you for your quick response. I looked up Robber Fly on the What’s That Bug page and did find pics that looked just like the bug on my tomato cage.
Thanks again,
Deana Campbell

What's That Bug? does not endorse extermination

Subject: red footed
Location: alabama
July 26, 2014 2:49 pm
Does this thing bite or sting humans?
Signature: freaked out

Redfooted Cannibalfly eats Paper Wasp

Red-Footed Cannibalfly eats Paper Wasp

Dear freaked out,
Though the Red-Footed Cannibalfly,
Promachus rufipes, is a very adept hunter capable of taking stinging wasps like this Paper Wasp on the wing, they are not aggressive towards humans.  With that said, if a human ever tried to capture a Red-Footed Cannibalfly or other large Robber Fly with bare hands, a bite may result.

What's That Bug? does not endorse extermination

Subject: A Fly Or A Bee?
Location: Torrance, California
July 24, 2014 9:49 am
Dear Bugman,
By the end of June of this year, we found a couple of these insects in our front yard. The bigger one was about one inch long. We live in Torrance, California, and have never seen them before. Could you help us to identify them?
Thanks.
Signature: Daniel.

Bee Killer:  Mallophora fautrix

Bee Killer: Mallophora fautrix

Dear Daniel,
This Robber Fly in the genus
Mallophora goes by the collective general name of Bee Killer.  Your particular Bee Killer is Mallophora fautrix, a species with no specific common name, but according to BugGuide, it is:  “The only one of its genus in California.”  As you can see from the images in our links, Bee Killers prey on large flying insects other than Bees, and it is a rare, top of the insect food chain predator that preys upon adult, stinging wasps.  Though you are not the discoverer of a new species, you can spearhead a campaign to nominate the only Bee Killer in California as the California Bee Killer, even though its range extends beyond our fair state.

What's That Bug? does not endorse extermination