Hi Becky,

Those are fungus gnats. They do feed on decaying organic matter and that is usually a component of the soil. If you are getting it repeatedly, then it is probably because the soil you are using for the cuttings is contaminated with the fungus gnat larvae.

Try using a soilless, peat-based potting mix and move you cuttings into this mix and use a small pot. Keep the soil barely damp, but not constantly moist.

The flying gnats will die on their own within a week. If you get rid of the infested soil, you shouldn't have any future problems. If you do, let me know and I will provide further treatment instructions.