Diptera.info

Posted by bonitin on 25-12-2009 12:33

Hi,
I found this pretty Syrphid on the 22nd of May this year in a local Nature Reserve with lots of Wetland in Gent, Belgium.
Not sure if it is a male or female as these are tricky ones I thought?
Thanks!

img192.imageshack.us/img192/8982/239d.jpg

Posted by bonitin on 25-12-2009 20:44

Hi Pierre!

Thanks but I don't think it is H.pendulus..
because of: H.pendulus has a black middle stripe on its face, then the bands though at first sight much alike, do differ too, the eyes of H.pendulus are much darker, also its antennae, these are orange-yellow in this fly. It also looks more hairy overall..

Posted by PIERRE MILLE on 26-12-2009 17:43

Hi bonitin

I'm sorry! with us we say "I give my tongue of the cat " which means I do not see that in this case. In your opinion what is the genus name?

Posted by bonitin on 26-12-2009 23:15

Hi, Pierre,

I have given the name in the thread title above of what I think is my fly; Parhelophilus versicolor.

I wanted a confirmation as there is another very much alike ;Parhelophilus fruticorum who's very hard to distingish from P.versicolor only by some subtle details one of them being the colours of the hairs on the back side of the head, behind the eyes. P.versicolor has them all yellow while P.fruticorum has a row of black hairs there, I cannot see in my fly.
The Parhelophilus genus is one of the tricky exceptions among the usual rule that females have separate eyes whiles males have them closer together or joined.
Males in this genus have them seperate too..

This is a Helophilus pendulus for you to compare

img52.imageshack.us/img52/7149/helophiluspendulus8.jpg

Posted by PIERRE MILLE on 27-12-2009 16:08

Hi Bonitin,

That's interesting ! I never knew there could be exceptions to distinguish females and males. I checked and it is not easy to distinguish.

http://syrphidae.3644.co.uk/index.html
I did some research and discovered that in the genus Parhelophilus and specifically P. frutetorum ago profile of the male's head with a yellow callus and femur 3 (posterior) of the male form as a kind of bump.
I find it very informative