Dear All, I have used a product called Knock-Out Gnats sold by Gardens Alive! that uses Bt. You have to use it in all your pots in that vicinity and they recommend a soil drench for three weeks in a row to get successive generations of larvae. It seemed to worked. As someone else mentioned a friend of mine said having insectivorous plants in her greenhouse banished them as well. I ordered some Drosera seeds from Silverhill but so far they haven't germinated. Drosera is a geophyte. Does anyone on this list grow it? Mary Sue