100% fungus gnats.

You're probably over watering your plant. They are attracted to moisture and decaying matter in the soil. They're harmless to you and your plants but they're annoying as hell.

Instead of pesticides, try repotting it in drier soil with better drainage and water it less. The larva lives in the soil. Vacuum the adults (shown), clean the window area and repot.

Don't put rocks at the bottom of a pot for drainage - it leaves a pool of water for the roots to rot in and the gnats to be attracted to. You don't need stones or sand on the soil either. Use a good soil mix with perlite (the white stuff in potting soil) and stop watering so much.