Probably fungus gnats: not really harmful, but a blamed nuiscance! They may also be a symptom of overwatering, or too much raw organic matter in the mix, which may cause other problems this summer. Try sprinkling mosquito granules around, first. That has a form of B.t. that affects larvae of members of the fly family: mosquitos, gnats, and flies. Beneficial nematodes also help, if you can find them, but they only stay during cool weather. Another possibility is a product containing cedar oil, which burns out the gnat's smelling sensors, disorienting them, and making mating impossible. Be advised that the gnats will also colonize houseplant soil, and sink drains.

Good luck with the little critters!
Kevin : )

If you have hummingbirds, you may notice them coming along for dinner, they hover above my compost pile and fill up :o) then off to feed the little ones at home. Obviously I'm OK with them outside :o)

I'm infested with them too, because of all the rain. As it warms up and dries out, there will be fewer of them.

Get a moisture meter for plants and be sure you aren't over-watering.

Lucky for me they are in a raised container with wheels, so I'll be moving to a more sunny area of the patio this weekend to dry up the soil.