dipteran mating display?

[Don.Colless at CSIRO.AU]

Ken:

Would you consider a mosquito? The size seems about right, and many species rest normally in just the position you describe. I suspect that receptors in the hind legs, probably at the apex of the femora, are being raised to an optimal position. 

-----Original Message-----
From:   Taxacom Discussion List on behalf of Ken Kinman
Sent:   Mon 8/23/2004 12:26 PM
To:     TAXACOM at LISTSERV.NHM.KU.EDU
Cc:	
Subject:             dipteran mating display?
Dear All,
      Especially to entomologists on the list.  I know next to nothing about mating displays in flies, but a gnat (ca. 4 mm. long) crawling on my door window caught my eye.  It seemed to be displaying in a way that is reminiscent of male jumping spiders trying to attract a female.  However, the appendages being raised by this gnat seem to be the third (posterior) pair of legs thrust upwards and arching somewhat forward towards the head.  After putting the gnat in a vial, it continued doing this, so I thought perhaps it might be a threat posture as well.

      Anyway, I'm just wondering if this is some kind of posturing that certain male gnats usually do, and if so, to what family of gnats might it belong?
           ----- Thanks,
                          Ken