Tired of Gnats Swarming Outside? Try 4 These Simple Fixes Before They Take Over

If you’re finding an overflow of gnats outside your home, it can be a huge nuisance. Gnats aren’t all bad—they decompose organic matter, pollinate flowers, and serve and as a food source for large insects, birds, and bats—but large numbers of these pests make lounging outdoors unenjoyable. Plus, some can pose a threat to your garden plants.

Read on to learn about when outdoor gnats are becoming a problem, how to get rid of them, and prevent them from infesting your home. 

What Attracts Gnats Outside Your Home

The typical yard contains lots of sources that potentially attract gnats: moisture and humidity, dampness, dense plant life, and decomposing organic matter.

Gnats thrive in temperatures between 75 and 80°F and populations often visibly increase in extended rainy periods. They’re attracted to decomposing matter and standing water, so removing trash promptly and being mindful of water sources is the first step of gnat control.

Eliminating all the sources that attract gnats is impossible and would be detrimental to creating a beautiful landscape and balanced ecosystem, but you can at least control their populations by eliminating some of the most obvious sources.

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How to Control Gnats Outside

To reduce gnat populations, gnats need to be targeted at the larval stage; this is when they damage plants. Getting rid of gnat adults by spraying them with pesticide will do more damage than good and kill beneficial insects.

Eliminating the sources that attract gnats is your first line of defense. It may require more than one measure to get rid of gnats.

Remove Stagnant Water

Clean up any standing water and places where water accumulates, such as clogged storm drains, drain pipes, and gutters. Be mindful to fix any outdoor plumbing or irrigation system leaks, too. This is where gnats grow and mate.

Avoid Wet Soil

Wet soil is a primary source of fungus gnats, indoors as well as outdoors. Improving poor drainage around established plants is tricky, but the least you can do is adjust your watering schedule. Only water plants when the soil is dry, and always let the soil dry completely before the next watering.

Remove Organic Debris

Gnats like to lay their eggs in moist decomposing organic matter such as grass clippings, compost, and mulches. Collect any organic debris around your yard and avoid applying more organic fertilizers (compost, manure, blood meal) than necessary, especially in wet weather.

For potted plants, only use pasteurized potting soil as the organic matter in it may be infested with fungus gnats.

Use Biological Control

An effective way to control gnats is to add beneficial nematodes to the soil. These tiny worms kill the pests without affecting other beneficial insects—plus, they multiply in the soil so there is a long-term effect. This is sold in powder form and added with water to the soil. 

Types of Gnats

Gnat is the common name for several small, winged insects with long legs. They mate in swarms and multiply rapidly and in large numbers, laying their eggs on land or water.

Insects commonly referred to as gnats include:

• Drain flies: Also known as sink flies or sewer flies, they are found around drains, sewers, and septic tanks.
• Phorid flies: Like drain flies, they are found around garbage, drains, rotting fruits and vegetables, and other decaying organic matter.
• Fruit flies: These pesky indoor pests are attracted to lots of organic materials such as rotting or fresh fruits and vegetables, sugary drinks, wine, and vinegar.
• Fungus gnats: Mostly a problem of houseplants, fungus gnats can also damage outdoor plants by transmitting disease. The larvae of fungus gnats feed on plant roots, causing leaves to turn yellow and drop or causing plant wilting and death.

Preventing Future Infestations

In addition to following the control methods above, monitoring your plants for gnats is another good way to reduce gnat population before they turn into an infestation. Look for the adults on soil, plants, or in flight; yellow sticky traps are useful for monitoring population numbers.

If any of your patio plants are infested, don’t move them to a different area because they might infest other nearby plants.

Keeping Gnats Away From Your Home

Just as gnats outdoors, gnats indoors are attracted by moisture and rotting organic matter. Closely inspect every potted plant before bringing it into your home. This applies both to newly bought houseplants as well as plants that spent the summer on your patio and that you bring back indoors for the winter.

If you are not sure whether the plant has fungus gnats, play it safe and turn the top 2 to 3 inches of soil over and let it dry out to kill the larvae. If a plant is visibly infested, it’s better to get rid of it.