Edymnion is incorrect in his/her explanation of fungus gnats. In our homes and greenhouses, they are not necessarily fungus feeders though their populations certainly explode under the moist conditions that mold/fungi thrive in. They feed upon decomposed or decomposing organic matter, such as the stuff that (most) of our potting mediums are comprised of, algae, fungi (if there is any in your potting mix (not in mine!!), and plant roots. Ohiofem explained it perfectly...a few of these little insects are not something to worry about. But they (the tiny, maggoty larvae) will begin to feed on tender plant roots as their populations rise. That's why we worry about it when our seedling trays become infested. Many germination mediums and even common potting mixes are very fine textured and peaty...a perfect (though artificial) environment for fungus gnats, even it you don't keep it too moist all of the time. Inside, where there is no place else for the adults to lay eggs, our containerized plants can soon become over-run with the larvae. At this time of year, you can find mosquito dunks at most garden centers and even hardware stores. Break a few pieces from a dunk and let it soak in your full watering bucket over night. Use that water for your plants. For the next several watering cycles, use the 'dunk' water only. Mosquito dunks contain a naturally occurring bacterium that affects the larvae of certain insects, such as mosquitoes, black flies (of the northeast), some shore flies, and fungus gnats. The larvae feed on the dunks and the ingested bacterium infects them. This bacterium, named Bacillus thuringiensis-israelensis (Bt-i) is harmless to anything but the targeted larvae. Next time, search for a much coarser potting mix, one that cannot support fungus gnat larvae. Such a medium can still be used as a germination mix by using a shallow layer of the peaty stuff on top of the coarser material. Also, as has been said, moisture levels need to be monitored carefully. These insects really love very moist medium. My potting soil, for example, contains more pine bark than peat moss. I haven't seen a fungus gnat in many, many years.

Just a guess, but there were probably just a lot more ants being eaten than gnats. Once ants find a food source, they send in the reinforcements. Gnats are not that organized. Also they are probably a bit more substantial for the plant.

I don't think there's a better feeling than when you create something with your own hands and it turns out better than you imagined. It feels good to sit back and take it all in. I upgraded my setup yesterday. I added cross beams on the top and an additional shelf. I'm up to 3 lights now, and I doubt that will be enough. I have some peppers(under the towel) germinating on the bottom. Seedlings are under the lights, while cucumbers, tomatoes, and cantaloupes are on the top. Congrats on the successful DIY project. Hopefully your season will turn out just as good. Tim

It's a multi-step program. First, you might want to take a good look at your potting medium. Perhaps it doesn't drain rapidly enough or is simply too fine-textured. Second, make sure that you aren't watering too much (frequently), which can be easy to do it the potting medium is not a good one. Keep the greenhouse floor as clean as possible. Provide good air circulation. Then, applications of Gnatrol (or other Bt-i) during your normal watering regime will get rid of the larvae, if you follow the directions. Repeat applications will be required, of course, until all of the existing adults are dead and gone.