Currently viewing the category: "Thick Headed Flies"

Subject:  Fly ID
Geographic location of the bug:  Aurora, Ontario. Canada
Date: 05/04/2019
Time: 11:14 AM EDT
Your letter to the bugman:  Hi!
Could you please help me with ID of this fly? I guess it’s some kind of hoverfly
How you want your letter signed:  Vladimir Morozov


Dear Vladimir,
Your images are beautiful.  We are relatively confident this is not a Hover Fly, but we are uncertain of its family.  We are leaning towards Tachinidae, but we are currently battling very slow internet in Ohio which makes research ponderous.  Perhaps one of our readers will recognize this Fly.

Thick Headed Fly

Comment from Cesar Crash
Mouthparts, calyptra and halteres don’t look like Tachinidae. I think it’s Zodion sp.  See BugGuide.

Daniel, Cesar  thank you very much. Really looks like some Zodion

Subject: Chalcid wasp?
Location: Peterborough ON
May 26, 2016 9:02 pm
I found these small (1mm+) wasp-like insects mating in my backyard on the weekend – May 24. It was sunny and warm: around 26C.
Signature: Rob Tonus

Mating Tiny Flies

Mating Thick-Headed Flies

Dear Rob,
Our initial impression that the faces on your mating insects looked more like Flies than Chalcid Wasps proved correct when we zoomed in on your very high resolution image, which revealed the presence of halteres which are defined on Entmologists’ Glossary as “modified wings. In the Diptera (true flies) it is the hind wings that have become halteres. …  Halteres are shaped like ‘drum sticks’ with a slender shaft connected to the thorax at one end and ending in a thicker structure at the other. Halteres are highly sophisticated balance organs and they oscillate during flight.”  So these are mating Flies.  We are going to post your submission as unidentified while we continue to research the identity of your mating pair of Flies.  We will also contact Eric Eaton to get his input.

Eric Eaton Responds
Sure:  Thick-headed flies, family Conopidae, maybe Myopa for genus?

Ed. Note:  This image on BugGuide looks very close, but it is listed as 12mm, not 1mm.  According to BugGuide:  “Myopa species are parasitic on Honey Bees Apis mellifera, Andrena and Mustache Bees Anthophora.”

Thanks so much for the quick feedback, Daniel.  I appreciate you investigating these mystery insects for me.

Thanks again for this additional information.
The flies were larger than 1 mm, but much smaller than 12 mm – perhaps 5 or 6 mm at most . . . that’s only an estimate, though, since I saw them mating, and they could have had their abdomens twisted, which made them look shorter.
Are these presumptions on genus the closest we’ll get to identifying them?  Is it difficult to determine species without having them in hand?

Perhaps a Dipterist may be able to do a conclusive species ID, but alas, we have not the necessary skills.

Subject: Fly indentification please
Location: Illinois, usa
March 16, 2014 11:42 am
Hello! My name is Shawn from Connecticut. I run an insect page on instagram and am quite careful when identifying insects. This here was sent to me to identify from Illinois. I first thought it was a type of fly or perhaps a mosquito, but I am leaning more towards fly. I’d greatly appreciate your insight. Thank you very much, Shawn.
Signature: Shawn Dean (iamshawndean)

Fly on Flower

Fly on Flower

Dear Shawn,
Our first thought was that this must be a Flower Fly in the family Syrphidae, but we were unable to locate a matching image on BugGuide.  We will attempt continued research.

Karl identifies a Thick Headed Fly
Hi Daniel and Shawn:
This is a variety of Thick-headed Fly (Conopidae) in the subfamily Stylogastrinae and genus Stylogaster. There are only two species of Sylogaster in the USA, S. neglecta and S. biannulate. Stylogaster neglecta appears to be the closer match and the long ovipositor indicates that it is a female. The female uses this ovipositor to pierce the body of a host orthopteran (cockroach, cricket, grasshopper or katydid) where the deposited egg becomes an endoparasite. Regards. Karl

Oh thank you so so very much Daniel. I greatly appreciate your efforts. I utilize the information on your page all the time and truly appreciate everyone who works so hard to bring us the most accurate information you can.
Thank you again,
Shawn Dean

We have updated the posting with a correction identifying this as a Thick Headed Fly, Stylogaster neglecta.

Subject:  thick headed fly
Location:  Lancaster, PA
October 30, 2013  10:12 AM
Hi again
Don’t mean to be a pest, but thought you might be able to use some shots of thick headed-flies making maggots. I took these in my flower garden on Joe Pye weed, Lancaster PA. There are abundant bumble bees which I imagine is why they’re hanging around.
Melody McFarland

Mating Thick Headed Flies

Mating Thick Headed Flies

Hi Melody,
Pest?  You have provided our archives with two marvelous additions of underrepresented species on our site.  We only had two Thick Headed Fly images in the category, but because of posting your submission, we realized that we had several additional older postings that were never categorized.  According to BugGuide, Thick Headed Flies in the family Conopidae are “usually found on flowers” and “Adults take nectar. Larvae are endoparasites of wasps, bees, ants, crickets, cockroaches, and some Diptera (mostly calyptrate); host group varies by subfamily.”

Mating Thick Headed Flies

Mating Thick Headed Flies

We are trying to post a few last minute submissions as we will be away from the office for the next week without internet connectivity.

Thick Headed Fly

Thick Headed Fly

Identify a Wasp with a white face?
Location:  Fairfield, Maine
August 3, 2010 7:45 pm
I found this on some goldenrod along with dozens of paper wasps. I seemed very camera shy or very busy, so I was only able to get this one picture. I looked through a lot of the potter wasps but did not find anything with the same markings and colors. Is this even a wasp at all?
James R

Unknown Syrphid Fly

Hi James,
This is not a wasp, but a fly that mimics a wasp.  We suspect it is in the family Syrphidae, the members of which are called Flower Flies or Hover Flies.  We are posting your photo as unidentified until we get an actual species or at least genus name.  Perhaps our readers can assist us.

Correction thanks to Karl
August 4, 2010
This is a Thick-headed Fly [see BugGuide] (Conopidae), so named because of their relatively large heads. According to the Kaufman Field Guide to Insects of North America “They are mostly parasites of adult solitary bees, and sometimes wasps. The female fly assaults the host in midair, often forcing it to the ground and ramming an egg between the victim’s abdominal segments before releasing it.”  I believe the genus is either Physocephala or Phyoconops, the difference apparently being that in Physocephala the hind femur is somewhat swollen at the base, whereas in Physoconops it is not. This feature is not always easy to distinguish but the femurs do appear slightly swollen in this individual. There are many very similar looking species but based on color patterns of the face, legs, wings and abdomen, I think this may be Physocephala marginata. Regards. Karl

Thick-headed Bug Love
July 14, 2010
Found some thick-headed flies courting and thought you might like them for your bug love page. They were mating until I rudely interrupted with my camera, poor things.
central NJ

Mating Thick Headed Flies

Hi Sara,
We keep on saying this is the last letter we are posting today, and we keep finding awesome letters and photos, but we really need to stop with your awesome images of Thick Headed Flies in the family Conopidae.