Bringing up the topic of gnats tends to conjure varying degrees of annoyance. Whether you’re an aspiring gardener, or simply taking a walk by the water during the right season, chances are you’ve noticed – or ran right into – clouds of these tiny flies that suspiciously resemble mosquitoes.
Luckily for us, gnats don’t bite, nor do they transmit or carry diseases. They’re not harmful to humans, except when it comes to the nuisance spectrum. Fungus gnats, which are the most common species of gnats, are often found infesting plants around the house, hanging around lights or commercial greenhouses, or congregating in other damp places like sink drains or garbage disposals.
Why Gnats Are Attracted to Our Plants and Home
Fungus gnats live and die quickly, with a life cycle reaching up to a grand total of about three weeks. Adults can live up to one week, spending that time laying up to 200 eggs in the top layers of moist plant soil. These eggs take a few days to hatch, after which larvae chomp away at or even burrow inside of plant roots for about a week – though they can also munch on mulch, mold, clippings, compost, or even fungi. Once they finish up their pupal stages, which takes another four days, adult gnats emerge from the soil to begin this cycle once more.
Because gnats operate on such a condensed timeline, infested house plants may often house several generations of gnats at once, according to the Pennsylvania State University. That makes it all the more challenging to get rid of them, if you do end up unwittingly bringing home a plant with gnats. This is everything you need to know about gnats and moreover, how to get rid of them safely.
Read More: Why Are We Afraid of Bugs?
How to Get Rid of Gnats
The general rule of thumb when it comes to getting rid of gnats is to change your watering habits. Indeed, according to the Oklahoma State University, overwatering is often the culprit, creating the ideal damp environment for adult gnats to lay their eggs and live.
Allowing plants to dry in between waterings – particularly the top couple inches of soil where gnats tend to lay their eggs – and also maintaining proper drainage is key to fixing up a gnat-friendly environment. Moreover, keeping up this habit also prevents the growth of fungus, which attracts the aptly named fungus gnat.
Additionally, experts also recommend checking humidity levels to ensure they’re not too high and cleaning up any fallen leaves or debris that may harbor moisture and decay.
Finally, placing your plant in quarantine for a few weeks, especially if it’s been outside potentially gathering up gnats, can also reduce the risk of bringing an infestation home.
Keeping Gnats Out of the Kitchen
In the kitchen, gnats may be drawn to the wetness of sink or garbage disposal drains, or foods that have gone bad on the counters. Better Homes & Gardens recommends getting rid of any food products that may have begun rotting, while also pouring a diluted mix of bleach and water down the drain in order to clear out any gnats hanging around there.
Other tricks to trap gnats include vinegar and sugar traps. Mix vinegar with water and a few drops of dish or liquid hand soap – or you could use red wine instead. The soap ensures that gnats who enter the trap can’t fly back out. Instead of soap, you could also opt for covering the dish with plastic wrap and poking small holes on top.
Protecting Your Houseplants
If you see your house plants suspiciously wilting or yellowing, chances are it might not be your fault: It could be gnats. But since plants can carry gnats in all phases of their lives, at once, the method of treating gnat infestations will differ depending on the stages of development.
To monitor adult gnats and trap them, experts recommend putting up yellow sticky traps near plant leaves – these are relatively inexpensive and can easily be purchased online.
Besides ensuring that plant soil dries sufficiently before watering, you can further protect your growing medium by spreading a layer of gravel or coarse sand. This protects soil and deters adult female gnats from laying their eggs in such a dry environment. It may take a few weeks of these modified regiments before results start to show – but know that persistence is key.
Another alternative to watering plants from the typical top-down direction is to go bottom-up. Placing the plant in a dish filled with water allows its roots to soak up the moisture and keep your plant hydrated, without wetting the soil up top, where gnat larvae tend to live. However, it’s important to keep the pot’s drainage hole from leaking or open to gnats, lest it worsen the problem even more.
Outdoor Gnat Control
Gnats can also congregate in the great outdoors, typically around light. To combat this, try switching your bright light bulbs for ones that emit a warmer, yellower color – rather than cool white-blue – so gnats are less attracted to them.
Fixing up any spots that might be leaking water, such as wayward pipes or wet fountains, will also reduce moisture in your garden, which will ward off gnats seeking egg-laying spots.
Read More: How to Turn Your Yard Into a Wildlife Oasis
Getting Rid of Gnat Larvae
As for targeting gnat larvae, the University of California’s Statewide Integrated Pest Management Program recommends using: potatoes. Placing slices of raw potatoes on the surface of your growing medium attracts larvae, who will emerge to feed on the potato tissue. While this can lead larvae away from plant roots, you’ll want to make sure to check for maggots after a few days.
Alternatively, you can fight gnat larvae with predatory mites on your own. Nematodes are microscopic worms and great examples of biological control agents. They target gnat larvae by burrowing into any orifices they have, from mouth to even their anus, and then release bacterium that digests larvae from the inside.
It will likely take multiple rounds of nematode soaks to get rid of all gnat larvae, but these little worms are a sufficient method of cutting off the development of future gnat generations.
Ultimately, it’s a combination of these methods that can do the trick. Insecticides are an option, but they should always be a last resort, as most times, simply changing the environmental conditions of your house plants should be effective enough.
Next time you accidentally attract a cloud of pesky gnats into your home, know that while gnats can seem persistent – even painfully so – all you have to do is be a bit stubborn, too.
Read More: Do Insects Have Feelings and Consciousness?
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
Joshua’s Pest Control. How to Get Rid of Gnats Outside
Penn State Extension. Fungus Gnats in Indoor Plants
Oklahoma State University. Get Control of Fungus Gnats on Houseplants
Lookout Pest Control. How to Prevent Gnats and Fruit Flies in Your House
Better Homes and Gardens. How to Get Rid of Gnats in Your Home and Garden (for Good)
Wisconsin Horticulture. Fungus Gnats on Houseplants
Los Angeles Times. How to really, truly, finally get rid of fungus gnats for good: We asked the pros
University of California Agriculture and Natural Resources. How to Manage Pests
Colorado State University. Fungus Gnats as Houseplant and Indoor Pests
