The ones I'm using are the Steinernema Feltiae. I've used them along with the mosquito dunks which I crumbled and put in the soil. I also put two dunks in a five gallon bucket and have been using it to water with since. I watered with the nematodes 10 or 11 days ago for the first time and I've pretty much explained above what I've done since and right now I don't see a single gnat flying around anymore. There was practically a cloud of them 10 days ago. So I can't say for sure it was the nematodes or the dunks but both of them together have been extremely effective.