Looks like a Gant!! Dude get rid of them fast..
If you have a lot flying around Google homemade Gant trap they work great
I had about over 30 gnats in my house, made the traps and they were all dead in the trap..
They work great..after killing the adult gnats go get some safe spray for the larvea they leave in the soil and will kill your plants
Trust me on this I been having the same problem right now and i'm barley getting the plants over it.