BTI and Fungus Gnats
From Summit Chemical’s website,
Because fungus gnats are closely related to mosquitoes, fungus gnat larvae are effectively killed by BTI—the naturally occurring bacterium that is deadly to mosquito larvae. BTI, short for Bacillus thuringiensis israelensis, is deadly to mosquito larvae and fungus gnat larvae but harmless to other living things. The bacterium is nature’s way of keeping fungus gnat and mosquito populations down, but it has no effect on other insects (such as bees and butterflies)—nor does it harm animals, fish, birds, plants, pets or people.
BTI is the active ingredient in top-selling Mosquito Bits®, which is approved for the control of fungus gnats. To kill fungus gnat larvae, simply shake the granular Mosquito Bits® onto the potting soil in houseplants and other container- grown plants, including vegetables and herbs. Mosquito Bits® can also be mixed with potting soil prior to planting. When the plants are watered, the BTI in the Mosquito Bits® will be released. After subsequent watering, the BTI is washed below the soil surface. Fungus gnat larvae feed on the BTI and die.