Fungus Gnats - What To Do

Fungus gnats are very annoying pests. Anyone who has grown houseplants for any length of time has likely seen these tiny, mosquito-like flies.
Fungus gnats love rich, damp organic soils and feed on the various fungi and other microorganisms that reside in these soils. A single adult gnat has a lifespan of about 10 days, but can lay about 250 to 300 eggs during that time. Eggs are laid into the soil and very tiny legless larvae emerge in a few days and feed before emerging from the soil as winged adults. Adult gnats don’t feed but are annoying flying around ones houseplants!
Control of Fungus Gnats is threefold. First, buy only high quality potting soil that drains well. Fungus Gnats love nothing better then consistently wet and boggy soils.
Secondly, use some yellow "sticky traps" to monitor and capture fungus gnat adults. The adults find anything that is bright yellow, irresistible.
Thirdly, there are sprays (we carry some here in the greenhouse) that can be applied directly to the soil and are very effective for controlling Fungus Gnat larvae. More than one application is necessary because sprays only affect the larvae and not the eggs.
While Fungus gnats are the least damaging of all the common houseplant pests they are the undisputed champions when it comes to indoor insect pests that people hate the most.