These images are of flies reared from larva collected in little bluestem (Schizachyrium scoparium). The larva hollow out the vegetative stem terminus then exit to pupate. The adults are approximately 4-5mm long.
It looks like a Psilidae. But if you want an expert view it could be a good idea to post it on www.diptera.info. There is a whole bunch of dipterist waiting for you ;-)
Abhijit, Thanks for the ID effort, but the fly is some form of picture wing. The P. casei is devoid of the dark areas on the wings. I've had a coouple other ID's suggested outside of this forum. One entomologist believes it's a Eustxesta spp. and another believes it's an example of the Physiphora spp.
I am sure this is not physiphora spp. If black banding patterns are present on wings then it may be of Euxesta spp. thank you William. Have a nice day.