Just can't find it

[DaiTheDragon]

Tried to ID this without success. Any help please.
Thanks.
Dai

[oxycera]

Mmm, I've never seen one but I wonder if this could be Dasystrphus 'hilaris' - neither am I sure of the current status of this 'species'.
Be interesting to get Roger's opinion.

[JRsbugs]

Looks like Dasysyrphus venustus female but you would need to see the face, D. venustus has a dark stripe where D. hilaris doesn't.

Of course Roger has mentioned there is a shake up going on with these but for the present that is how they are determined.

[oxycera]

There are other differences, obviously the face character would be key if you could see it

[JRsbugs]

Originally Posted by oxycera

There are other differences, obviously the face character would be key if you could see it

Could you tell me what the other differences are? I don't have a key for these and I don't think I have seen anything else mentioned on diptera.info.

Here's mine from 3rd May.. it looks the same, the spots on Dai's might look a little different due to the angle of the abdomen but I think there would be a little variation anyway.

[DaiTheDragon]

Thank you very much for your help. I must admit I always forget to try and get a shot of the face.

Dai

[Geoff F]

Janet, according to Stubbs; venustus has narrow dusting just at the sides of the frons and the hind tibia is completely yellow. Hilaris has more extensive dusting which covers half the width of the frons and there is a dark mark on the middle of the hind tibia.

There are a few other items about the extent of the yellow bars but these seem somewhat subjective.

[JRsbugs]

Originally Posted by Geoff F

Janet, according to Stubbs; venustus has narrow dusting just at the sides of the frons and the hind tibia is completely yellow. Hilaris has more extensive dusting which covers half the width of the frons and there is a dark mark on the middle of the hind tibia.

There are a few other items about the extent of the yellow bars but these seem somewhat subjective.

That's very interesting Geoff, mine doesn't have narrow dusting just at the sides of the frons, I would say it's quite broadly towards the middle such as you would see on Melanostoma scalare. The hind tibia is not completely yellow either! You're certain you didn't get the two mixed up?

[Geoff F]

You had better take that up with Mr. Stubbs, Janet

I definitely copied the information correctly. I would consider your specimen to be a variation of D. venustus. But I'm not a qualified expert.

The main useful extra items for separating these species are that the outer ends of the yellow bars are narrower in venustus (approx one quarter the length of the tergite compared with approx half in hilaris). Also the abdomen of venustus is more squat (two and a half times the length on tergite 3).

But in all honesty, the separation of these two species seems somewhat unclear and Stubbs states that 'hybridisation may account for intermediates'.

Some pale faced venustus specimens have been found and some hilaris have a rather weak facial stripe.

Perhaps one for Roger to consider.

One other point, which probably won't help, is that venustus has a strong black band on sternite 2 while hilaris is mostly yellow.

[Jason Green]

Evening all,

Originally Posted by JRsbugs

That's very interesting Geoff, mine doesn't have narrow dusting just at the sides of the frons, I would say it's quite broadly towards the middle such as you would see on Melanostoma scalare. The hind tibia is not completely yellow either! You're certain you didn't get the two mixed up?

...maybe you need to get Stubbs yourself. See the complicated stages first-hand - and just check on whether your Dasysyrphus dets are in fact, correct. Don't forget dusting can be photographically-affected by light, and then may not always be reliably on show.

Take care,

Jason