Currently viewing the category: "Thick Headed Flies"
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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.

What's That Bug? does not endorse extermination

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

What's That Bug? does not endorse extermination

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?
Thanks!
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

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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.
Sara
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.

What's That Bug? does not endorse extermination

Thick-headed fly
July 11, 2010
Thick-headed fly
Sure thought this was a smallish wasp, but finally found out it’s a thick-headed fly. Thought you might like a picture.
Sara
NJ

Thick Headed Fly

Hi Sara,
As we were working on your post, we realized we needed to create a new category for Thick Headed Flies.  We will need to search through our archives to see if we have any older postings of Thick Headed Flies in the family Conopidae, but this might be a first for our website.  We believe your specimen may be in the genus
Physocephala, which BugGuide describes as “adults feed on flower nectar  Females usually oviposit on hosts (mostly bumble bees and wasps) during flight. Larvae become internal parasitoids (usually kill the host).“  There is additional clarification of the life cycle on BugGuide:  “P. tibialis has been reported to parasitize workers of the bumble bee Bombus bimaculatus. Adults apparently alight and inject an egg into the abdomen of their host while in flight.  A study in Alberta showed that bumble bees parasitized by P. texana had the same lifespan as unparasitized individuals (Otterstatter et al, 2002; …).

Ed. Note: A previous posting of a Thick Headed Fly from 2009 was added to the new category.


What's That Bug? does not endorse extermination

Thick-headed fly
July 25, 2009
Here is a photo I took today. Went to Buguide. It was identified as a conopidae, species unknown. Posably physoconops, or physocephala.
Terry Sincheff
Mound, MN

Thick Headed Fly

Thick Headed Fly

Dear Terry,
Thanks so much for sending us your photo of a Thick Headed Fly.  WE are linking to the BugGuide information page that states:  “The adults are usually found on flowers.  Food  Larvae are endoparasites, chiefly of adult bumblebees and wasps. Adults take nectar.

What's That Bug? does not endorse extermination