A search and destroy of one gnat at a time may provide some brief relief, but how can you get rid of gnats completely? Start with the larvae.
“The most effective control methods target these immature stages, rather than attempting to directly control the mobile, short-lived adults,” according to the University of California‘s integrated pest management program.
Other strategies include keeping excess moisture in your plant soil to a minimum, setting traps, and using natural gnat predators.
Is it Really a Gnat?
If it looks like a gnat, flies like a gnat, and annoys like a gnat, it must be a gnat, right? Not necessarily. Gnats are often confused with fruit flies and drain flies (they’re all super small and pesky, so we get it). But while fruit flies are tan-colored with red eyes and drain flies have a more moth-like appearance, gnats are dark-colored and drawn to water.
Three types of tiny flies tend to carry the “gnat” name: biting midges, eye gnats, and fungus gnats. The latter is the type most often found in homes and the ones we’ll focus on helping you get rid of. These fungus gnats love to congregate around potted houseplants and drains. Since they’re also attracted to light, you’ve probably caught them flying near your computer screen, light bulbs, and windows, too.
About 1/8 to 1/10 of an inch in length when fully grown, fungus gnats live all over the world and can be a bother in any season. Harmless to humans — they don’t bite or spread diseases — these pests feed on fungi, algae, plant roots, and mold in soil.
Despite the adults being mere nuisances to people, an infestation of the larvae they create can damage plant roots and inhibit growth.
These tiny, winged insects reproduce rapidly with females laying up to 1,000 eggs during their 10 days of life. From this beginning stage to adulthood takes about four weeks, and the cycle continues — unless you bring it to a halt.
How to Get Rid of Gnats
When they’re not lounging on plant leaves or depositing offspring into the soil, fungus gnats are on a quest through the rest of your home.
Here are a few natural and chemical tactics to end their exploration.
Getting rid of gnats naturally
The first step in preventing any type of insect infestation is to maintain a clean, uncluttered home, as to limit their opportunities to multiply. For gnats, specifically, you can also install specialized screens and detect and repair any leaks. Other natural ways to get rid of gnats include:
1. Houseplant management. If you notice these pests swarming around your pots, your soil is likely infested. Fungus gnats thrive on moist soil, so a quick way to shorten their stay is to let the soil dry out completely before watering the plant again. Before potting any new indoor plants, opt for pre-treated, pasteurized soil mixes like the ones sold in stores, rather than compost from your own pile. Alternatively, you can evict fungus gnats by setting the affected plants outside.
2. Fungus gnat traps. UC’s integrated pest management program suggests placing sticky paper on garden spikes to catch adult fliers and using cut, raw potatoes to catch larvae. Toss full traps and repeat the process as needed.
3. Dryer sheets. A 2010 study brought credibility to this long-held belief. Only effective on the adult population, the chemicals in dryer sheets proved to repel gnats. Try placing them in containers near windowsills, on desks, or anywhere else you’ve seen these pests appear.
Essential oils may also do the trick. There are no definitive studies yet, but the dryer sheets’ repellent scents derive from plants, including lavender and basil.
4. Natural predators. Another option is to purchase nematodes, rove beetles, or predatory mites, which feed on fungus gnats. These critters will arrive in the mail and should be applied to your soil immediately. Since these organisms reproduce on their own, they can provide lasting gnat control.
Getting rid of gnats with chemicals
For use inside your home, pesticides should be a last resort. But, if the natural methods haven’t worked as well as you’d hoped, try a spray made with pyrethrin, a component of the chrysanthemum flower. Keep in mind that this method only works on adult fungus gnats and doesn’t solve your problem long-term.
Colorado State University’s Extension recommends insecticide formulations using imidacloprid, as well. This type of gnat killer is sold as granules and as slow-release spikes you can place directly in your houseplant’s soil. And this option can also kill the larvae.
Other Questions About Fungus Gnat Infestations
We’ve discussed how gnat offspring is more harmful (to plants) than adults, but are there any particular houseplants these pests attack most? According to Penn State’s Extension, yes. Well, sort of. The soil and roots of any plant can provide the nourishment newborn gnats need to grow and develop. However, plants that may attract these insects most are African violets, poinsettias, geraniums, cyclamens, and carnations.
Besides seeing swarms of adult gnats flying around and discovering white-colored larvae in the soil, other telltale signs gnats have attacked your plant include wilting, discoloration, and stunted growth.
In your research on how to get rid of gnats, you’ve probably also seen mentions of using neem oil and dishwashing soap to combat these pests. But do they really work?
Colorado State’s Extension suggests they may, but only for a short time. You’ll need to apply multiple applications every few days, and these remedies won’t kill your problem at its source — the larvae.
When to Call in the Pest Control Pros
Whether DIY’s not really your thing, or you need a solution that’ll pack a more powerful punch, schedule an appointment with a local pest control professional. They’ll confirm your problem and develop a customized treatment plan to solve it.
To prevent future recurrences, take care to store pasteurized soil in airtight containers, so it stays gnat-free and ready for your next use.
Other ways to keep away gnats? Clean your home regularly and don’t overwater your houseplants.
Main Photo: Katja Schulz / Wikimedia Commons / CC BY 2.0
