Fungus gnats are swarming around the containers because of too moist conditions, or a potting medium that is too mucky (peaty) and holds on to water longer than it should. The gnats lay their eggs in the potting medium and the larvae, if populations are high enough, can do damage to plants by nibbling on roots.

Are they fire ants in the containers, or another species? If so, you can bait with Amdro outside of the containers (not inside). There are also ant BAIT products on the market containing the active ingredient Spinosad. It's considered safe to use with food crops.

Purchase some ordinary mosquito dunks. Break one into small pieces and put part of the dunk into a watering can (or two) for several hours. Then, water your plants as usual. Each time you have to water those containers for the next few days, use the mosquito dunk water.

Active ingredient is Bacillus thuringiensis Israelensis, a naturally occuring biological control for certain members of the gnat and mosquito families. Mosquito dunks are manufactured for use as a larvacide for mosquitoes. You can also purchase something called Gnatrol, which is made to be mixed with water to water the soil.

Next year, find a recipe to make great, coarse textured potting soil that cannot support fungus gnat larvae. You and your plants will be much happier.

Mix vermiculite / perlite into your soil mix. It will make it drain quicker and the plants will grow better - the fungus gnats will not have anything to eat so they reduce in number. Make sure the dunks contain BTi - some dunks do not (they contain chemicals that can harm some plants) Some fungus gnat products cannot be purchased in washington state (the dunks can be)