Another of the little gnats that hang out on my computer screen at night. Probably the same as the two below, one of which was identified as Sciaridae.
Unlike that one, this has claspers on the end of the abdomen. I think that makes this one male and the other female.
These guys are fairly active, hopping about. To get this shot I finally made use of the UV filters the camera shop sold me along with my digital SLR. Place filter on screen to trap fly, slip index card underneath, put second filter against other side of card, remove index card from between them. Insect trap. It calmed down eventually, otherwise I would have restored to chilling.
This is, in the full size, about a 1.9:1 macro (2.6 microns per pixel) using a Tamron 90mm lens and 68mm of extension tubes.