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Hi,
I am very curious if this case could be solved:

upon dissecting the head of a female Tabanus sudeticus, a larva appeared near the esophagus, so it was probably sitting in the thorax. It was about 3mm long.
Is there anything known about Tabanids being the host of other flies? Can the larva be narrowed down to a certain family?

Cheers,
Lorin

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I'm not sure, but what about the larva of a parasitic wasp? It doesn't remind me of a diptera larvae. But I'm curious too.

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well, a wasp came to my mind in first place - but I was thinking the mouth hooks were characteristic for a dipteran larva. Happy to learn more :-)

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this is very interesting. I don't recognize the larva but hopefully someone does.
very nice discovery, Lorin!

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any idea whom I could approach to find out more?

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if Paul Beuk or Theo Zeegers has no opinion, then i don't know of a Tabanidae specialist. Fauna Europaea lists Dr. Chvala but i don't recommend contacting him. He is old and not very helpful. I've written to him before about Hilara. He seems disinterested in helping.

Dr. Bystrowski is very nice and very helpful. You could ask him for an opinion if noone answers. He may even be able to recommend a specialist if you ask him about it.

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Hi Carnifex,

The head looks like a Hymenopterous larvae. But the anterior spiracle looks highly unlikely for a Hyemnopterous larvae. There is no real pharyngeal skeleton visible. So it cannot be a acalyptrate or calyptrate larvae, as far as I know.

There are Braconidae (Euphorinae) which parasitize adult holometabolus insects such as Coccinellidae (Coleoptera) and Bombus sp. (Apoidea).

In the Diptera family Pipunculidae there are species in the genus Nephrocerus which parasitize other adult Diptera of the family Tipulidae.

Also a possibility that it is a very young larvae of Tabanidae which hatched and was somewhere in your sample.

For an accurate identification a better picture of both the head and the posterior spiracle would be needed.

Hope this helps,

Greetings,
Ectemnius

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Hi there,

I finally got access to a better optic device. Unfortunately I did not image the posterior spiracle in detail, but maybe from the mouthparts some rough classification is already possible?

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and here two views of the mouth parts

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K.G.V.Smith (1989, An introduction to the immature..., p.20) mentioned the paper of Thompson 1978 recording Macronychia and some Tachinidae from tabanids in the US. Maybe you are the first in Europe who noticed these parasites?

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To me, the mouth hooks look more like those found in Oestridae (bot fly) larvae. So I'm wondering whether this is an accidentally ingested larva that the Tabanus has picked up off its host. Perhaps someone with experience of freshly-hatched oestrid larvae could offer an opinion?

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That sounds all very interesting, I will try to make better images when I get a slot at the microscope again. Otherwise, I am also willing to send the sample to someone who wants to take a look at it

Cheers!