Currently viewing the category: "Mydas Flies"
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Large Wasp in AZ
Location: Tuwhicson, AZ
June 24, 2011 8:52 pm
Hello,
I took this picture of this huge wasp-type insect in Tucson, AZ and I’ve been trying to figure out what it is. It was maybe about 1.5” – 2” in length. The closest-resembling thing I’ve been able to find is the tarantula hawk, but I’ve only read about those having black abdomens/bodies with orange wings. Can you please identify my bug?? Thanks!!
Best,
Brooke
Signature: Brooke

Mydas Fly

Hi Brooke,
This is not a Wasp.  At first we thought it might be a Robber Fly, and we found a Robber Fly from Arizona on BugGuide,
Archilestris magnificus, that is colored similarly, but alas, the antennae are quite different.  We then shifted to what our first impression was, that this might be a Mydas Fly, and we found a photo from Colorado on BugGuide of Phyllomydas phyllocerus  which matches quite nicely.  Additionally, there is a nice closeup of a related individual from Florida on BugGuide that also looks close.  We cannot say for certain that either the genus or species is correct, but we are relatively certain that this is in fact a Mydas Fly.

Hi Daniel,
Thanks for your help and your quick response!!!  Your website is excellent.  I started thinking after I posted my photo that it might be a fly because of the trumpet-shaped thing coming out of its face/mouth – or whatever flies bite/suck with.  I’m not up on my insect terminology.  That is one huge fly!  I’m relieved to know that it’s not a tarantula hawk.
Thanks again,
Brooke

Hi Brooke,
You are correct that wasps and flies have very different mouth anatomies.  Flies have a proboscis designed for sucking up food, and wasps have mandibles for chewing food.  Here is how the Utah Education Network website describes the mouth of a fly:  “Flies cannot chew. They have to suck up their food. Flies have mouth parts that absorb food like a sponge. Their food has to be in a liquid form in order for them to eat it. They have a tongue shaped like a drinking straw to slurp up their meals. Flies that eat nectar or blood do so by using their tongue which is called a proboscis. Even flies that eat other insects do so by sucking out the insides of their victims.”

Eric Eaton confirms ID
Daniel:
Sure looks like a Mydas sp. to me.  Nice detective work!
Eric

What's That Bug? does not endorse extermination

peach borer or mimic?
Location: powhatan county, virginia
June 17, 2011 10:22 am
there is a low-cut, decomposing stump in my flower bed, from a tree felled many years ago (hardwood, not fruit). when tending the flowers, i noticed and collected this insect, as well as several pupae cases (from which another like insect was emerging), from around the base of the stump on june 16, 2011.
i am not convinced it is a peach borer, because the antennae are very different, as are the eyes/head – more fly-like. the orange band is higher up on the abdomen, and the wings at rest fold over one another. i’m fairly certain it has only one set of wings. any info would be appreciated!
Signature: bugwatcher

Mydas Fly

Hi bugwatcher,
This incredible creature is a Mydas Fly,
Mydas clavatus, and according to BugGuide, it is a:  “Large black fly with red/orange mark on top (dorsum) of 2nd abdominal segment. Body hairless, cylindrical. Eyes large. Antennae are distinctively clubbed in the Mydidae. This species flies rather boldly in the open. With the black-and-orange pattern, it resembles a wasp and fools the casual observer.”  The larvae live in compost piles, soil and rotting wood where they feed on June Beetle Larvae.  According to BugGuide:  “Eggs are laid singly in soil or rotting wood. (See video of oviposition–Flickr). Mydas larvae prey on beetle larvae, esp. those of June beetles. Larvae pupate close to soil (or wood?) surface. Adults are active only in mid-summer. Mating system in this species unknown.”  You are observant in noticing that the Mydas Fly, in addition to mimicking Spider Wasps, looks very similar to a female Peach Tree Borer.  The Peach Tree Borers are also wasp mimics, as you can see in this photo from our archives.

Mydas Fly Pupa

thank you so much. the more i talked about fly characteristics, i looked up all the flies on your site, and found Mydas after i had sent my email. i was thrilled to discover what it was, and promptly let it go. a beautiful fly, and a garden helper at that. when it flies, it has a very nice low buzz, also wasp-like and intimidating. i feel fortunate to have been able to examine it so closely during it’s brief adult stage. thank you again for your prompt response and devotion to the site.

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What is this bug?
June 14, 2010
This guy has been around the yard a couple times now. Pretty good size, maybe 1-1/2″ or so, jet black except for an orange band around it’s abdomen.
Thanks, Ben Hanson
Port Charlotte Florida

Mydas Fly

Hi Ben,
We received an email from you on May 21, and we posted your photo of a Mydas Fly.  This is another view of the same species of Mydas Fly, Mydas clavatus.  We apologize if we did not write back to you directly, but your previous letter has been on our site since then.  We are postdating this letter to post live to our site during our absence in the coming week so that our readership will continue to get daily updates.

Daniel;
Thanks so much for the reply and information! I might have missed an earlier reply…
Thank you people for what you do. Your site and Facebook page is very highly entertaining and informative!
Ben

What's That Bug? does not endorse extermination

Scarab hunter wasp?
May 21, 2010
Never seen anything like this intimidating looking insect. Maybe close to two inches long? It looks similar to those published on your website….
Ben
Port Charlotte Florida

Mydas Fly

Hi Ben,
This is a Mydas Fly, Mydas clavatus, and you can read more about Mydas Flies on BugGuide.  Your observations are astute.  A Mydas Fly, according to BugGuide:  “Resembles a wasp of the family Pompilidae, and is presumably a Batesian mimic.
”  BugGuide also indicates:  “Mydas larvae prey on beetle larvae, esp. those of June beetles.

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Black Robber Fly ?
July 15, 2009
This is a common fly in my garden this summer. There may be as many as five of them that have set up territories throughout my strawberries, squash, and tomatoes. It resembles a robber fly in the way it perches on vantage points and quickly flies away when disturbed in the slightest. It sometimes seems aggressive and will even investigate me when I attempt to photograph it. This is a large black fly that I suspect is over an inch in length and has orange, lateral, very round, spots, one on either side of the abdomen near the thorax. Some of the individuals have light yellow spots and others have brighter orange spots. I have never seen one with prey, as I do the other recognizable species of robber flies in the garden. This picture was taken in mid-July during some of the hottest days of summer in Oklahoma. Rain has been sparse and the ground is very dry except around the garden that is regularly watered and attracts several species of insect.
K. Hopkins
Oklahoma, USA

Mydas Fly

Mydas Fly

Dear K.,
This is a Mydas Fly, Mydas clavatus.  According to BugGuide:  “I have seen adults (males?) of this species taking nectar from several sources in Durham, North Carolina. I have seen a female ovipositing in a dead maple stump. Later, I found this stump was full of carpenter ants and large beetle larvae (probably Odontoaenius disjunctus). I have not observed the adults taking prey on the wing. Sources vary on the feeding habits of adults. Most say the adults are predatory, but this may be incorrect. Perhaps this is due to confusion with the somewhat similar Robber Flies (Asilidae)?”
BugGuide also indicates that male Mydas Flies engage in Hilltopping, which Wikipedia explains as a mate-location behavior where “Males of many butterfly species may be found flying up to and staying on a hilltop – for days on end if necessary. Females, desirous of mating, fly up the hill. Males dash around the top, competing for the best part of the area – usually the very top; as the male with the best territory at the top of the hill would have the best chance of mating with the occasional female, who knows the ‘top male’ must be strong and thus genetically fit. Many authors consider this as a form of lekking behaviour.[4] Many butterfly species including swallowtails, nymphalids, metal-marks and lycaenids are known to hill-top.”

What's That Bug? does not endorse extermination

Mydas clavatus – Mydas Fly
Mon, Jul 6, 2009 at 1:59 PM
I know you have some pictures of this already but I can’t help but send this to you anyway. I found this on my blooming mint plants today and thought it was a huge wasp. A search on bugguide showed me that it was instead one of the largest flies in the US a mydas fly. Looks like it must be a male as they say females don’t feed on nectar. He is jet black with a brilliant orange stripe on the upper abdomen with Iridescent wings. Looked to be about 1 1/2 inches in length. Not aggressive but focused on nectar gathering.
Surely is an amazingly beautiful creature!
Stefanie
Paducah, KY

Mydas Fly

Mydas Fly

Hi Stefanie,
Thank you for sending us your gorgeous Mydas Fly images.  We will link to the BugGuide page for our readers who want more information on this spectacular insect.

Mydas Fly

Mydas Fly

What's That Bug? does not endorse extermination