Gnats are pesky and persistent little buggers that reproduce quickly and discreetly, making it tricky to find where they might be coming from. The good news is that, as annoying as gnats are, the ones you're noticing inside are likely harmless. But how do you get them to go away, and how can you be sure that you're not dealing with biting insects?
What Do Gnats Look Like?
Found throughout North America, fungus gnats, part of the Mycetophilia species, are typically the culprits when it comes to indoor gnat issues, though you could be seeing drain flies, fruit flies, biting gnats, midges, or mosquitoes, all of which can be mistaken for gnats.
Fungus gnats are typically somewhere between 1/8 and 1/4 inch in length (4 to 7mm) and can be brown, black, or yellowish in color. Fungus gnats do not bite.
Outside, fungus gnats can be found in shady and moist environments and are most active in the summer months. Adult female fungus gnats lay their eggs in soil where their larvae eat decaying plant and organic matter. Lucky for the gnats that want to move inside, many people have interior house plants, which provide fungus gnats with a year-round feeding and breeding source. Inside, keep an eye out for these pests flitting around light fixtures and windows.
If you have interior house plants and think you have fungus gnats but aren't sure, yellow sticky traps can be placed in your plant pots near the base of the plant. This will help determine if there is any fungus gnat activity in the soil.
Fungus gnats have a very distinct odor when crushed between your fingers. If you're up for it, catch one, squish it, and take a whiff. Do you smell a strong, fungus-like odor? If so, you're likely dealing with fungus gnats.
3 Ways to Get Rid of Gnats
Address Moist Soil
Wet soil is an attractant for many pests. If the soil in or around your home tends to be overly moist, try letting it dry out a little more between waterings to discourage gnats and other pests from being attracted to it.
If you have houseplants, make sure that they are not being overwatered, as this creates a year-round breeding and feeding source inside your home for gnats and other pests.
If your houseplants are the source of your gnat issue, don't despair! Kill off any larvae in the soil of your houseplants by digging down two to three inches and turning the top of the soil over. Don't water it! Allow the soil to dry out, which will kill the larvae in the soil. Lastly, place 1 to 2 inches of sand on top of the soil. This will discourage standing water and keep the gnats from being able to lay eggs there.
Install Light Traps
Light traps can be installed inside and outside to discourage gnats. Interior light traps will help keep inside gnats and other nuisance pest populations at a manageable level. Exterior light traps can help discourage gnats from entering your home in the first place, but they must be brighter and more exciting to the pests outside than the lights they can see inside your home.
Clean up Sources of Organic Material
Gnats and many of their lookalikes are attracted to rotting organic materials. Whether it's damp potting soil and plant matter, scummy residue in drain pipes, or rotting food in a compost bin, these sources need to be addressed if you want to get a handle on the issue.
Don't overwater your soil, clean out your drains with a stiff scrub brush and drain cleaner, and make sure your compost bin has a tight lid.
Even a leaky pipe that is causing minimal mold or wood-rot can provide gnats and other pests with a food and water source. If you can't find the source of your issue but know it must be somewhere, think outside the box to determine where it could be.
Signs of a Gnat Infestation
Sometimes called "no-see-ums" due to their incredibly tiny size, gnats are very commonly confused with a variety of other flying pests (including phorid flies). If you are finding small, flying insects inside your home and you want to get rid of them, first determine which pest is causing the issue. Every pest is different and it's important to know what you're dealing with before formulating a treatment plan. Unlike with other pests, though, your first hint of a problem will usually be seeing the flies themselves flitting around, not discovering their droppings, nests, or other evidence.
What Causes Gnats?
When determining what type of tiny flying pest is invading your home, start by asking yourself the following questions:
- Where are you finding them most?
- What might they feeding on?
- Where could they be finding water?
Gnats and small flies that appear inside homes are drawn to rotting organic matter, which they use for both a feeding and breeding site. To get rid of them, you are going to want to address as many of these sources as you can.
If you can, try to get an intact sample or picture. The more detailed or close-up, the better! Identification between pests can be very tricky, and being able to reference a photo while you research will make finding answers that much easier for you.
How to Prevent Gnats in Your Home
Whether you're dealing with gnats or one of the many pests mistaken for them, you can prevent an ongoing issue by focusing on sanitation: Once the food source or breeding site of the pest is cleaned up (or never allowed to linger in the first place), the issue should be resolved.
Fungus Gnats, or Something Else?
It's easy to mistake one small fly for another. A gnat infestation is often fungus gnats, but your unwelcome flying visitors could also be drain flies, fruit flies, biting gnats, midges, or mosquitoes. Learn how to tell the difference so as to properly identify and address your pest problem.
This tiny gnat look-alike has lots of names. Sometimes called moth flies because of their resemblance to a tiny, powdery moth, these flies are around 1/8 inch (4mm) in length with long antennae and light tan to gray coloring. They have faint black and white speckling on their heart-shaped wings and small white hairs on their body. These flies do not bite, but drain flies can come with other concerns.
It is common for people to think they are dealing with gnats when they are in fact seeing drain flies. Are you noticing small flying insects in your bathroom? While not exclusive to bathrooms, drain flies (also called bathroom flies) feed on the scum, moisture, and rotting organic matter that accumulates in places like bathroom drains. This problem can be solved by adequately cleaning drains, but know that pouring bleach or drain cleaner down the drain is not enough. This will kill adult pests but will not kill the larvae or adequately remove the feeding and breeding source. Drains must be scrubbed out with a drain cleaner and a stiff scrub brush.
Drain flies can sometimes transmit disease because of where they hang out, especially when the fly issue is severe. They can fall into food, causing asthmatic reactions and making swallowing and breathing difficult. If you have a drain fly issue, try to address it as quickly as possible before it becomes unmanageable and hazardous.
Another pest commonly confused with interior or fungus gnats are fruit flies, also known as vinegar flies. These flies are incredibly small, around 1/16 inch (2mm) with distinct red eyes and a mix of tan, black, and grey on their head and body. They do not bite, but can be quite a bother.
These flies are so small, they can pass through ordinary screening used to keep other flies away. They are common in houses, especially kitchens, as well as restaurants and other food handling sites. They have also been known to carry disease. Aside from vinegar, they are attracted to droppings and uncooked food.
There are a number of biting gnats, including the buffalo gnat, the eye gnat, and the Clear Lake gnat (which is native to a specific area of California). These gnats are all drawn to moist outdoor environments with plenty of rotting organic material perfect for laying eggs in and feeding on. If you are dealing with interior gnats, any of these varieties of biting gnats are likely not the guilty pests, but if you live in a wetland-type area, you may want to take preventative measures to keep these nasty guys outside where they belong.
Exterior light traps can be effective in keeping exterior biting gnat populations at bay. If you are installing an exterior light trap, make sure that it is brighter and more attractive to the gnats than the interior lights shining through the windows. Otherwise, you could be drawing the gnats in rather than keeping them out.
Midges and Mosquitoes
These pests are frequently referred to as gnats, even though they don't look much like them up close. Keep in mind that midges and mosquitoes are much bigger than a gnat is. While both are generally outdoor pests, they can both end up inside, especially during summer evenings when it is warm and they are attracted to sources of light around the home.
While very different from the gnats they're often confused with, mosquitoes and midges look and behave very similarly to each other. Both seek out standing water (which is where they lay their eggs), both are known for swarming (especially at dusk), and both are attracted to light. Mosquitoes are notorious for their blood-sucking bite, but midges are completely harmless and have fluffy antennae that make them easy to identify. They also do not have a proboscis and do not suck blood. Not sure if you're dealing with mosquitoes or midges? Look for the fuzzy antennae.
What Is a Proboscis?
A proboscis is the long, straw-like mouthpart that mosquitoes and other insects use for sucking or piercing.
Will gnats go away on their own?
If the gnats are outside, they are a seasonal issue, and populations will shift with the changing seasons. Inside, they can become a year-round issue and aren't likely to go away on their own. If gnats have found their way inside and you're noticing them regularly, there is something in your house that is attracting them and providing them with what they need to survive. Find what's attracting them and address it and the issue should resolve itself.
Do gnats bite?
While there are some species of biting gnats, they do not generally infest indoor spaces. If you are noticing gnats inside, it is likely a fungus gnat or a type of fly that looks similar to them, in which case you shouldn't need to worry about biting.
When to Call a Pro
With interior gnat and fly issues, once the feeding/breeding source is addressed, the issue will likely resolve itself. If you are inspecting for the cause and having trouble finding where the gnats or flies could be coming from, this might be the time to call in a professional IPM specialist to help you inspect.
“Gnats.” Home & Garden Information Center | Clemson University, South Carolina,
Mallis, Arnold. The Handbook of Pest Control: The Behavior, Life History, and Control of Household Pests. Mallis Technical Handbook and Training Company, 2011.