Posted by Calilasseia on 02-08-2012 03:12
#1
The photos I'm posting in this thread are of a fly species unknown to me, but which I suspect the experts here will be able to track down with far greater ease than myself. The data is as follows:
Location: UK, OS Grid Reference SJ496853, 01 Aug 2012, between 16:30 and 16:50. Conditions mild and sunny, following approximately 1 hour of rainfall.
Observed behaviour: numerous individuals observed performing "dances" upon leaves of Bramble plants (
Rubus fruticosus), the largest leaves with the widest expanse of open space apparently being the prime choice of site for this activity. Dances consist of rapid fluttering wing movements, with the wings being moved extremely rapidly in the horizontal plane, from the fully folded position to a position that appears to be about 20° swept back from the fully outstretched position (as the wing sweep would be measured on an aircraft, for example). Unable to determine the sex of the individuals at this juncture, and therefore unable to determine if the "dance" is a territorial display between males, or a courtship display to females. Scrub vegetation where this activity takes place is adjacent to both an open playing field, and a copse of trees including at least one confirmed specimen of one of the Oaks (
Quercus sp), Rowan or Mountain Ash (
Sorbus aucuparia), and several Sycamore trees (
Acer pseudopatanus). First photo is of typical choice of leaf for display purposes. Next post will hopefully contain a close up photo of the insect, if the uploading is successful!
Attachment now follows.
Edited by Calilasseia on 02-08-2012 07:28
Posted by Calilasseia on 02-08-2012 03:13
#2
Next attachment is a close up photo of the fly in question, which is also visible in the first photo. Hopefully this photo will be good enough to facilitate at least a Family placement, if not better. :)
Posted by Calilasseia on 02-08-2012 03:14
#3
And finally, another close up of the same specimen, which again is hopefully sufficient to facilitate at least a Family placement!
Posted by John Carr on 02-08-2012 03:20
#4
Poecilobothrus male, probably
P. nobilitatus. Females lack the white spot on the wing. Male Dolichopodinae often flutter their wings as a sexual display.
Posted by Calilasseia on 02-08-2012 07:27
#5
Thanks John! I'll annotate the files accordingly!
So what I've been observing is male courtship ... I'll remember to look out and see if I can see the unmarked females they're displaying to, and if I can persuade them not to take off, try and shoot some video footage of them as well as still photos.
Is my description of the fluttering display applicable to the entire Subfamily, or merely to certain species within said Subfamily?