Thread subject: Diptera.info :: Three Asilids

Posted by Juergen Peters on 29-07-2006 23:20
#1

Hello!

I found these robber flies today here in Ostwestfalen/Germany at a forest edge. The couple should be Choerades. Is it possible to determine the species?

#2 was about 12 mm long, #3 somewhat bigger. I have no real idea about these. Any hints appreciated. Thanks!

insekteninfos.de/forum/060729/Choerades_sp_1.jpg
insekteninfos.de/forum/060729/Choerades_sp_2.jpg

Larger pictures (~ 250 KB each):
http://insektenin...s_sp_3.jpg
http://insektenin...s_sp_4.jpg


#2:
insekteninfos.de/forum/060729/Asilidae_spp_12mm.jpg

#3:
insekteninfos.de/forum/060729/Asilidae_spp_15mm.jpg

Posted by Tony Irwin on 03-08-2006 17:08
#2

Hi Juergen
The couple are a happy pair of Choerades femorata, easily confused with marginata, but distinguished with a long first antennal segment (more than 3 times as long as the second).
I think numbers 2 and 3 are both Machimus, and I would suggest atricapillus.
Number 3 is displayng the typical asymmetric pose which this species adopts in sunlight, positioning one side of the body to obtain maximum heat (for efficient flight) while reducing the visible shadow, so making it less visible to avain predators.

Edited by Tony Irwin on 03-08-2006 17:09

Posted by Juergen Peters on 05-08-2006 21:54
#3

Hello, Tony!

Thank you very much for your explanations!