Posted by nick upton on 04-04-2012 15:10
#1
Is this small black fly on a dandelion a Fanniidae, maybe Fannia sp. or an Anthomyiidae. I'm not sure how to separate them..
Edited by nick upton on 06-04-2012 16:32
Posted by Stephen R on 05-04-2012 11:10
#2
This is an anthomyiid.
On the left wing you can see that the first anal vein ('vein 6') is long, reaching the wing margin. In Fanniidae this vein is short and the second anal vein ('v. 7') curves round to take its place - see the Gallery images.
Also there is a prominent angle between the parafrontal and parafacial strips (at the inner margin of the eyes next to the base of the antennae), making for a head shape that we wouldn't expect in Fannia. And we can see below the abdomen the processes of the 5th sternite which are prominent in some male anthos but never (as far as I know) in Fannia.
The course of the subcosta is often a good clue, but you can't see it well here.
On the hind tibia the obvious setae are clearly posterodorsal in position and direction. Fannia usually has two (sometimes one) strictly dorsal setae closer to the apex of the tibia.
Edited by Stephen R on 05-04-2012 11:11
Posted by nick upton on 05-04-2012 11:19
#3
Many thanks Stephen for taking the time to tell me the salient details to look for. That really helps!
Posted by Sara21392 on 05-04-2012 11:22
#4
Stephen, thanks so much, it was very useful to me! :D