Not only are fungus gnats a nuisance by buzzing around you when you water your houseplants, they also lay their eggs in the damp potting soil. The larvae of the small insects then nibble on the roots. If you notice an infestation of fungus gnats, you should not wait too long, but fight the insects at an early stage.
The eggs of the insects are often introduced into the potting soil of new plants, and potting soil that is kept moist also promotes the rapid growth of the fungus gnat population.
There are several methods to get rid of fungus gnats, we present the most gentle and promising ones. Of course, there are also chemical agents that help. However, you should avoid these if possible. If you follow the tips below, fungus gnats should no longer be a problem.
Quartz sand and yellow sticker
To combat fungus gnats, you should water your plants less frequently and never spread the water over the potting soil. It is better to pour from below, into the planter or the drip tray.
You should also cover the top layer of the potting soil with one to two centimeters of quartz sand (see Amazon) so that the fungus gnats can no longer lay eggs.
Yellow stickers can help: These yellow stickers (also yellow boards or yellow plugs, see Amazon) are simply stuck into the ground and, like fly traps, have an adhesive side to which the fungus gnats stick. These stickers also help with aphids.
There is also a very effective method with nematodes (see Amazon): These are very small roundworms that feed on the eggs of the fungus gnat, but leave the plant itself undamaged.
If you do not want to use nematodes, you can also use neem products (view at Amazon). As the name suggests, these products contain an extract from the plant parts of the neem tree (Azadirachta indica), which is known to provide effective protection against pests and diseases. However, you should limit the application to indoor plants and follow the protective measures described on the package. Neem extracts are toxic and it is forbidden to use them outdoors.