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I've spotted this phasia species last saturday. I had never seen such a fly before.

I asked what kind of fly it could be on another forum, they told me it is a phasia hemiptera. But i am not convinced this is a hemiptera, because of the crown and missing yellow on some parts of his body.

When i visited this site my eyes were drawn to the fly on the homepage (phasia aurigera), it does have many similarities with the fly on my pictures. The only thing im not sure about is its back, the drawings seems to differ a bit.

Which phasia is it? An aurigera, a hemiptera, or even another phasia?

Side:


Top (not fully sharp but gives a nice view of the crown):


Back:

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Where in the world are you?

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I live in the Netherlands.

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I think it has to be an Ectophasia crassipennis (male), but the photos are a bit indistinct. Have a look at the photos and text here: http://tachinidae...rcno=15901 :)

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Hi Chris,

I don't know anything about the variation of the coloration of the thorax, but it seems different in the specimens of "xenion". These flies look a lot like the one on the homepage of Diptera.info.

Jan Willem

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Hi Jan Willem, You might be right - looking closer the photos appear to show a petiole, so it should be Phasia but I'm not sure of the species. The key seems to rely on the colour of the hind femur and the hair on the sides fo the thorax - both of which are not clear on the photos. Another one for Theo I think :D

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Difficult one as i can see :P
I will check for better pictures of the hind femur and side thorax when i'm back home this evening.

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Congratulations Xenion !

The pattern on the thorax is very distinctive ->
male Phasia aurigera.

One of the first from The Netherlands !

Could you please email me details ?

Thanks


Theo

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Cool :D

I'm glad i was not convinced it was the hemiptera
Thanks for the help guys :)

Going to mail you now Theo.

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Hello!

Is it possible that this species is expanding? I had seen it for the first time here in Ostwestfalen/Germany three years ago, meanwhile it is the most abundant Phasia species (much more than hemiptera or obesa) and seems to have two generations in spring and late summer. In the last days (pictures from yesterday) it was numerous on Solidago canadensis and Mentha blossoms. Do the females (second pic) also belong to P. aurigera?

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Hi Juergen,

Great!
You are quite right in all aspects:
male and female Phasia aurigera.
In hind view, the thoracic dorsum is slightly more prominent than in this picture, however, not even close to that of the male.

And yes, the species is expanding northwards very rapidly.

Thanks to you, we know there are coming (same happened 5 years ago with Ectophasia crassipennis).

Thanks for the superb picture


Theo

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Has anyone suggested why these Phasia are expanding their range? I think it's unlikely that the hosts are also expanding - most of them are probably quite widespread already - so what is enabling the flies to spread?

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Hello, Theo!



Thanks a lot for the confirmation!



I'm still waiting for it... Haven't seen that species myself here in Ostwestfalen, but the number of queries with photos of that fly from various places here in Germany has increased in several forums this year.