Is there anything I can buy at the Home Depot to kill these insects?

Thanks, I need help as soon as possible because they are dying even right now!

Rino

You may have both Fungus Gnats and Damping Off. Damping Off can kill seedlings quickly. The Fungus Gnats themselves (the adults) probably aren't hurting your seedlings, but they lay eggs that hatch into maggots that feed on the roots of your seedlings. They wouldn't kill your seedlings so quickly, but certainly could stunt their growth.

I control Fungus Gnat maggots in the soil by watering with a solution that includes some powdered Mosquito Dunks. I use them because I happen to have them on hand. They should be available locally in a home store or garden center. I place a dunk, or a piece of one, in a Ziploc bag, place it on a hard concrete surface, and pound it into powder with a hammer. I add that powder to the water that I water my seedlings with. Don't breath the dust and wash your hands after. However, any product that contains Bt and is labeled for fungus gnats should work.

ZM

What kind of seed germination set-up do you have; what's your potting soil like; soil temperatures vs. room temperature, air circulation, etc. If we had some further information, we could do more to steer you in the right direction next time.

This is how I created my little greenhouse in the patio closet. The three round pots are those where the Lisianthus are growing.