They are typically harmless to healthy plants - and humans - but can inflict extensive damage to seedlings; their presence can indicate more serious problems.

In houseplants, the presence of sciarids may indicate overwatering; they may be feeding on roots that have been immersed in water too long and are thus rotting, or the gnats may be attracted to fungus growing in saturated topsoil.

[13] The pests are sometimes also managed by placing a layer of sand[14][15] pebbles,[16] or indoor mulch on top of the soil around plants.

Commercial greenhouses typically employ the insect growth regulator diflubenzuron for control of fungus gnats and their larvae.

For example, Bacillus thuringiensis israelensis (BTI) is known to produce proteins that can kill fungus gnats larvae and some other insects like mosquitos.

[23] Mites of the species Stratiolaelaps scimitus (formerly known as "Hypoaspis miles") have also been shown to be effective at controlling fungus gnats.

Other methods for controlling fungus gnats include drenching the soil annually in an insecticidal soap.

There are a number of toxic and non-toxic methods of controlling sciarids and their larvae, including diatomaceous earth, powdered cinnamon,[5] or by placing smells they dislike around the plant such as dryer sheets or oils like lavender and peppermint.

[26] To investigate how bad the infestation possibly is, one can place cut-up pieces of potato onto the topsoil, and let them sit for about 72 hours.