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Hello everybody,

I took attached pictures last summer in the Dordogne. For the Tachinidae lovers among us: is it possible to draw conclusions concerning its id? If required I have more photo`s. A pity I was unable to make photo`s of the oviposition itself

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Well, if there are tachinids parasitising the larvae of Symphyta, this narrows down the options considerably if these larvae were to be parasitised, as the larvae are not regular caterpillars. ;)

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yes, Paul, you make me curious. Please, say what is it?

;)

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I dunno. Like I wrote elsewhere: I am no tachinid specialist. :P

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I was just kidding! I believe some Exorista species and a Bessa species is paratising on Hymenoptera?

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Well, I'm sorry, but the picture is not good enough to make a guess.

Theo

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Well, I'm sorry, but the picture is not good enough to make a guess.

Theo

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Theo, I have more photo`s of the animal. What details do you need in particular? I made a long series of photo`s, while observing the fly.
This one, however, was the only pictures which showed more or less clearly the fly and the host.

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Lovely tach/host photo but for an ID we need to see the head very clearly (are the eyes hairy? what's the arrangement of facial bristles? is the back of the head with white or black hairs?) also the arrangement of the scutellar bristles and abdomenal bristles is important ... and the bristles on the mid-tibia. :)

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I`ll see what I have, this evening.

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another picture

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and another

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Not a clear one, but here you can see she is laying eggs ( I presume she is oviparous)

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again, not very clear, between her victims

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HI Ruud


Nice pictures of the action !

So, question: were the eggs actually laid on the hosts, or on the plant nearby the host. It would seem the last ?
In that case, we are probably dealing with a Goniini.

Otherwise, it is still difficult to give a name.
the praealar bristle seems long, best seen in second picture. It is out of focus, but it is long. (it seemed short in the first).
the general habitus reminds me of Myxexoristops blondeli.
Good news: this is a Goniini on Symphyta.
Bad news: it seems the the formation of the bristles on the humeri doesn't fit. Maybe I'm tricked by the view of angle.

And, I would like to see the middle tibia: does it have 1 or more anterodorsal setae ?
That would help


Greetings

Theo

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Well, Theo, I checked but I am afraid I do not have a good, clear pic of the humeri or tibiae.
I have a dorsal one, which isn`t very sharp, but the wings are more or less visible. Does this help?

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Well, all pieces help !
I see 1 ad on the mid tibia, but very difficult to see.
then again, the humeral bristles seem really inconsistent with Myxexoristops.
I still have figured out the scutellar bristles. Which means they are either small or erect, probably.

Or, the praealar is small and it's a Blondeliini after all.
So, let me think till tomorrow.


Theo

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Hi Ruud

You didn't answer the question about the spot of oviposting:
On the prey or on the plant ?

Theo

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Hello Theo,

as far as I could see it was on the plant, not on the host.

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So, I checked the literature.
Given what we know of the biology, there are two likely candidates:

Myxexoristops
Bessa selecta.

Bessa probably lays its eggs on the host. Moreover, the picture definitely does not agree with Bessa.

So, I return to my gut feeling: Myxexoristops blondeli.
Maybe the point of view is misleading, as far as the humeral bristles are concerned.


Theo