How to Get Rid of Gnats

At the beach, in your house, in the yard, at your barbecue – gnats can be a terrible nuisance. They fly around your face as you try to swat them away, they land on your food, and some even bite. There are gnats that are more prevalent outdoors, near the water while others are typically found indoors. These tiny, pesky creatures may be a common insect, but are still shrouded in mystery. What exactly is a gnat? Where do gnats come from? Most of all, how do you get rid of gnats? You will find the answers to all those questions right here.

What are Gnats?

Gnats are actually a type of fly. They are usually very small and some are extremely tiny, measuring 1/8-inch long. While all gnats fly, the appearance of each type is specific to the various species. The taxonomy of gnats shows that they are classified in the order Diptera which is in the class Insecta, in the phylum Arthropoda. Flies and mosquitoes are also classified with gnats in this order – and the suborder Nematocera. [1]

The term gnat is used to describe the various species in this suborder, particularly in the families Sciaridae, Anisopodidae, and Mycetophilidae. Generally, gnats are small flies with two wings and often fly in swarms. However, different types of gnats have characteristics that are specific to their species. There are more than 150,000 identified species of gnats, flies, midges, maggots, and mosquitoes [2]

Gnats are also usually very difficult to control. One of the most common questions that pest control professionals receive is how to get rid of gnats in the house or outside. The typical answer is that only pros can get gnats under control, but that isn’t necessarily true. The key to control is knowing the type of gnat you are dealing with and identifying the point of origin. You need to know what is attracting them and take care of that – and that is usually dependent upon the type of gnat you are dealing with.

Types of Gnats

Most of the insects that people refer to as gnats are actually tiny flies or smaller types of Diptera. Still, they are considered gnats. In fact, in England, mosquitoes are called gnats – and they are indeed of the order Diptera [3], same as what we in the United States call gnats. Each type has certain characteristics that set it apart from other species. Knowing the differences as well as what causes gnats can be very useful if you want to learn how to get rid of gnats fast and effectively.

Biting Midges

Commonly called no see ums. They are a significant nuisance pest, mainly due to their bite which can be painful and itchy, causing painful, long lasting lesions in some. They are a particular nuisance for people engaging in outdoor activities like fisherman, gardeners, hunters, campers, hikers, and others. [4]

Appearance – Adults are less than 1/8-inch-long with a gray body. They have two wings that have dense hair coverage and segmented antennae. They are difficult to see due to their small size.

Attractants – Typically found in areas like salt marshes, wet organic soil. Are usually found around outlets and bodies of water like lakes and ponds.

Special Characteristics – Their diminutive size makes them difficult to see. People know they are being bitten but usually can’t see the pests. They are sometimes called sand flies, but they are different biological groups. Only females seek blood meals. Populations do not establish indoors or in humans or animals. Most prevalent at around dawn and dusk.

Buffalo Gnats

Also known as black flies or turkey gnats are little but hardy flies that bite humans, livestock, wildlife, and poultry. There is some concern that they may be vectors for disease due to their blood sucking behaviors in some females although not all species bite. [5] Non-biting species are known to be nuisances to humans, flying around the head and crawling into the nose, ears, mouth, or eyes.

Appearance – 5 to 15 mm black body, short antennae, large eyes, and large fan shaped wings. Some species may be orange or yellow.

Attractants – Flowing or standing water, aquatic areas and plants, concrete dams, stream channels lined in concrete, restoration of polluted streams.

Special Characteristics – Very difficult to control. Treatment is often aimed at larval stages but females can fly long distances and leave the site of larval development. They can return later and re-infest areas that have been treated.

Eye Gnats

Severe nuisance pests that are potential vectors for disease. Robust in tropical and subtropical regions of the world including within the U.S. They do not pierce the skin or bite, but the female is very persistent, crawling over the skin feeding at the mouth, nose, and eyes as well as open wounds. [6]

Appearance – 1/16 to 1/8-inch body that is gray or shiny black with legs that range from yellow to orange brown and small, transparent wings.

Attractants – Moist, sandy soil that is well drained and contains a great deal of organic matter.

Special Characteristics – Poor flyers but because of their small size can ride the wind for long distances. Non-biters but feed on sebaceous secretions, blood, animal sweat, or pus.

Fruit Flies

Most prevalent in late summer and fall, but can be problematic throughout the year. These flies seek out ripened, spoiled, or fermenting vegetables and fruits to lay their eggs. They can be brought into the home from the garden or grocery store. [7]

Appearance – Adult fruit flies are about 1/8-inch-long with a body that is tan in the front and black in the rear. They typically have red eyes and small transparent wings.

Attractants – Rotting, spoiled, fermented produce, even if only a portion of the fruit or vegetable is damaged or cracked.

Special Characteristics – Can lay eggs under the lid of home canned fruits or vegetables, or homemade beer, cider, or wine. The larvae, upon hatching, will work their way into the product. Can be very prolific and the population can get out of control in a short time. Only when the breeding areas are eliminated can an infestation be brought under control.

Fungus Gnats

Typically found around potted plants, greenhouses, interior plantscapes, and nurseries, these gnats are drawn to material that are sources of organic decomposition, feeding on organic matter in soil, fungi, and roots of plants. [8]

Appearance – Usually 1/16 to 1/8-inch-long, but some species can be up to ½ inch long. Bodies are dark with long, segmented antennae, and slender legs. Wings are dark. Overall, they appear delicate.

Attractants – Organic matter in soil, fungi, potting mix, and other organic decomposition sources. Attracted to light.

Special Characteristics – Do not bite or cause damage to plant. They are primarily nuisance insects, but if the population is large enough, they can stunt a plant’s growth and cause damage to the root.

Hessian Flies

Primarily an agricultural pest, can cause significant economic injury due to their ability to extensively damage wheat and other grain crops. They are not known to infest oat crops. [9]

Appearance – Black body that is approximately 1/8-inch long. Eggs in the female’s body give it a red hue. However, it is the larva that poses the risk to crops. Eggs are red, tiny, and often cannot be viewed with the naked eye. The larvae are also tiny and red.

Attractants – Grain crops including wheat, barley, triticale, and rye. Oat crops are not affected.

Special Characteristics – Adult flies are rarely noticed even in high damage areas. Larva are difficult to see. Rarely infest the home.

Moth Flies

Also known as the drain fly, sewage fly, or filter fly. Due to their known attractants and infestation sources, they pose a significant concern to homeowners. [10]

Appearance – About 1/10-inch-long with a dark gray body with light, “fuzzy” wings.

Attractants – Commonly found indoors on walls, sinks, and windows. Sources of infestations are usually floor drains, sinks, RV toilets, waste disposal areas, or sewage plants that are nearby.

Special Characteristics – Typically found indoors where sanitation plays a key factor in infestations. Population control involves removal of organic material where the flies breed including toilets, drains, plumbing pipes, etc.

Phorid Flies

Also known as scuttle flies, coffin flies, and humpback flies. Globally, there are more than 3,500 species, each varying in form and shape to some degree. The phorid fly, Euryplatea nanaknihali, is the smallest fly in the world. Certain species attack other insects including honey bees, red fire ants, bumble bees, and wasps. For these purposes, the species discusses here is the scuttle fly, or Megaselia scalaris which is commonly found in the home.

Appearance – The adult scuttle fly is about 3 mm in length and are yellow to light brown in color. They are shaped similar to mosquitoes with long, delicate wings and legs.

Attractants – Rotting produce, particularly tubers like onions or potatoes. Cracked or broken septic lines can also be a culprit. They also breed in cadavers and dead animals.

Special Characteristics – These flies tend to run across surfaces, somewhat erratically, as opposed to flying. This is one of the most identifying features of the insect.

Sand Flies

Sand flies are considered to be a significant public health issue because they are known vectors for several bacterial, viral, and protozoal organisms that cause disease in humans and animals. Of the 700 species of sand fly, only about 70 transmit disease.

Appearance – About 3 mm at maturity with narrow, silver-brown bodies and long legs. Wings are densely hairy resembling a moth and are held erect over the fly’s body to form a vertical “V”. Females require blood meals to mature eggs.

Attractants – Sand flies are nocturnal and prefer hiding in humid, dark places such as animal burrows, tree holes, and under rocks during the day. They feed on animals, wildlife, domestic animals, livestock, birds, rodents, and humans.

Special Characteristics – Found in the southern states including Louisiana, across to Florida, including Tennessee, Arkansas, as well as North and South Carolina. They can also be found as far north as Delaware and Maryland.

Lifecycle of Gnats

Biting Midges – The complete life cycle of the biting midge can take anywhere from two to six weeks, depending on the species. The female requires blood meals in order for eggs to mature.

Buffalo Gnats – The female takes a blood meal and develops 200 to 500 eggs in a single batch which they lay on or in flowing water or wet surfaces like aquatic grass blades. Most species will hatch in 4 to 30 days although some may not hatch for several months or longer. There are, on average, of 7 larval stages and can take from 1 to 6 months to develop.

Eye Gnats – Within 5 to 8 days after hatching, females start laying eggs below soil that has been freshly turned. The eggs are laid in groups of as much as 50 but over a 2 to 3-day period the female can lay 200 or as much as 400 eggs which hatch in 2 to 4 days.

Fruit Flies – The entire life cycle is completed in about 7 days – from egg to adult. Females will lay approximately 500 eggs within that lifecycle.

Fungus Gnats – The fungus gnat lifecycle it in four stages: egg, larva, pupa, and adult. The larval stage also has four stages. From egg to adult, the lifecycle is about 17 days. Warmer environments can speed this process.

Hessian Flies – Three to five days after eggs are laid, larva emerge. The larval stage is around eleven days. The pupal stage is seven to thirty-five days. Adults only live long enough to reproduce which is about two to three days.

Moth Flies – Adults lay eggs in summer and spring. Entire life cycle of moth flies from egg to adult is between 10 and 15 days.

Phorid Flies – The life cycle of the phorid fly can range from one to two months. Eggs develop depending on temperature. At 93 degrees, the eggs usually develop within about nine hours. Development from egg to adult is around 17 days.

Sandflies – The complete life cycle of the sand fly, from egg to adult is typically between 36 and 74 days, depending on factors including larval food quality and temperature.

Do Gnats carry Diseases?

Several species of gnats, like the sand fly, are known to carry certain diseases. [13] Many gnat bites, though, cause reactions, some severe, in people who are allergic to them. For instance, the black fly bite. can cause a reaction with symptoms that include fever, headache, swollen lymph nodes in the neck, and nausea. Midge flies, or no see ums, can cause large, itchy raised areas with swelling and inflammation. Flies that live and breed in waste or sewers can spread disease even if they do not bite; spreading it merely by contact. [14] Eye gnats have been known to be responsible for the spread of pink eye and other eye infections. [15] While the hessian fly does not directly affect humans, its presence among grain crops can be devastating. [16]

For the most part, though, gnats, though, are simply a nuisance.

How to Get Rid of Gnats Inside & Outside

The key to knowing how to kill gnats is knowing what is attracting to your home or property. In this guide you should have sufficient information to identify the species of gnat that you are dealing with and from there, read about the life cycle, attractants, and behaviors. Understanding what attract gnats and what causes gnats will go a long way in their eradication. Typically, a singular eradication method is not enough. If you don’t know what is drawing the gnats to your home or property, then they will simply return.

As a general rule, there are steps you can take to prevent gnats, making your home and property inhospitable to them.

Outdoors

Get rid of all standing water on your property including children’s toys, the crotch of trees, pet water dishes, flower pots, old tires, and other items that may be in your yard. If you have any areas in your yard that hold water or create a marshy environment you should build it up. The key is to get rid of any areas that hold water or where the soil may stay moist.

Flower pots, gardens, compost piles, and moist ground coverage can also attract gnats. Cover the compile pile or place it as far away from your home as possible. Do the same with gardens, flower pots, and greenhouses. If you have thick foliage near your home, you may want to cut it back. That environment attracts not only gnats, but mosquitoes and other household pests as well.

When outdoors wearing long sleeves and long pants can help prevent bites from gnats. Insect repellants that are sprayed on the skin work with some species of gnat, but not all. Citronella candles sometimes work, but not for all species. Gnat traps have been proven effective for some species of gnats, but you should place it on the farthest edge of your property as possible so you don’t inadvertently draw the gnats to where you are.

Indoors

Keeping gnats out of your home is not always easy. You can bring them home from the grocery story, inside from the garden, or simply attract them to your home by creating an environment that attracts them. Using screens on your windows and doors works in most cases, but some gnats are so tiny they can get in anyway. The biting midge is a prime example.

If you have plants in your home, let the soil dry completely between waterings. This will kill any gnats in the larval stages. You can also get rid of gnats by vacuuming them from around plants, window sills, and other areas. Don’t leave dishes soaking in the sink and don’t leave any standing water out on your counters.

To kill gnats inside, the first step is eliminating their food source. This is where knowing the type of gnat you are dealing with is useful. If you have gnats in your home, use this guide to identify them and find out what is likely attracting them. If you have moth flies, look for drain issues, sewage leaks, or leaks in the pipes under the sink or even in the walls. Even a drain catch with just a little bit of food can lead to a gnat feeding frenzy.

If you notice fruit flies in your house, look around for spoiled or fermenting produce. Even a forgotten potato that has rolled to the back of the cabinet or an onion that rolled behind the refrigerator can lead to a gnat infestation. Get rid of the spoiled fruit or vegetables and wipe down the area thoroughly. It also helps to keep fresh fruit and vegetables in the refrigerator, but when they start to spoil, toss them out. When disposing of spoiled produce, seal it in a plastic bag. Don’t leave it uncovered in the garbage can; this can still draw gnats.

There are insect traps that are designed to be used inside. The trap is plugged into an electrical outlet and it emits ultraviolet light rays. This attracts flying insects and they fly to it only to become trapped on the stuck surface of the device.

Sometimes, despite your best efforts, the gnats continue to invade your home. When that happens you may need to take a more aggressive approach to getting rid of gnats.

Pest Control for Gnats

When you are applying pest control products to treat gnats, again, you need to know the type of gnat you are fighting. That will help you determine the best product for getting rid of the gnats and killing the larvae – and showing you where to apply it.

Often, controlling gnats in your home requires a multi-step approach. A good Pyrethin Aerosol will knock out the adults that are flying around – on contact. You can also treat the breeding site and area where the eggs are laid – if you can find it. If you don’t get the larvae, then in a few days or weeks you will be right back where you started with a new generation of gnats flying about. Incorporating a fly trap into your home pest control for gnats will help as well. They also work for many different types of flying insects.

Once you have eliminated the breeding and feeding sources, you should spray a residual treatment. This is a good course of action for outside as well as inside. The residual will remain active and when the flies walk through it they will eat if off of their legs or it will get on their bodies where it will be circulated through their system and it will kill them.

If you have drain flies, you should also get a good drain cleaner and septic treatment product, both of which can be purchased through many DIY pest control stores. This will help rid your drains and sewer of material that may be trapped in the drains and pipes that is attracting the gnats.

Spraying a Pyrethin aerosol in your yard may help some, but it usually is not completely effective. A flying insect trap is usually your best bet. If you are having a gathering outside, like a barbecue or pool party, then you may want to use several. Typically, you don’t want it to be too close to the people because you don’t want to attract gnats to your party. However, you can take some time and experiment with placement a few days prior to your event.

Getting rid of gnats takes a great deal of diligence and consistency. It is a multi-faceted approach that involves educating yourself on the type of gnat, its habits, and what attracts it as well as where they are originating in your home or yard. This guide can help you do just that and your home can be free from gnats.

Sources:

1. Yeates, David K. (2016). Phylogeny of True Flies (Diptera): A 250-Million-Year-Old Success
   Story in Terrestrial Diversification, Retrieved from
   http://wwx.inhs.illinois.edu/research/flytree/flyphylogeny/
2. USDA – Agricultural Research Service. (2008, September 2). More Than 150,000 Species Of
   Flies, Gnats, Maggots, Midges, Mosquitoes Documented In Database. ScienceDaily.
   Retrieved July 1, 2016 from
   https://www.sciencedaily.com/releases/2008/08/080830161221.htm
3. “gnat.” The Columbia Encyclopedia, 6th ed. 2016. Retrieved July 01, 2016 from
   Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-gnat.html
4. Connelly, Roxanne C., “Biting Midges” University of Florida, Entomology and Nematology
   Department. (Reviewed 2016). Retrieved July 1, 2016 from
   http://entnemdept.ufl.edu/creatures/aquatic/biting_midges.htm
5. “black flies” Purdue University: Medical Entomology. 2008 Retrieved July 01, 2016 from
   https://extension.entm.purdue.edu/publichealth/insects/blackfly.html
6. “Pest Notes: Eye Gnats” University of California Statewide IPM Program. August 2013.
   Retrieved July 01, 2016 from http://ipm.ucanr.edu/PMG/PESTNOTES/pn74164.html
7. Potter, Michael. “fruit flies” Entomology at the University of Kentucky. (ND). Retrieved July 01, 2016 from https://entomology.ca.uky.edu/ef621
8. “Pest Notes: Fungus Gnats” University of California Statewide IPM Program. August 2010.
   Retrieved July 01, 2016 from http://ipm.ucanr.edu/PMG/PESTNOTES/pn7448.html
9. Chapin, J.W. “Hessian Fly: A Pest of Wheat, Triticale, Barley, and Rye” Clemson University
   Cooperative Extension. (Rev 08/2008). Retrieved July 1, 2016 from
   https://www.clemson.edu/extension/rowcrops/small_grains/pdfs/hessian_fly.pdf
10. Jacobs, Sr., Steve. “Moth Flies in the Home” Penn State College of Agricultural Sciences
    (Reviewed January 2014). Retrieved July 1, 2016 from
    http://ento.psu.edu/extension/factsheets/moth-flies-in-the-home
11. Jacobs, Sr., Steve. “Phorid Flies” Penn State College of Agricultural Sciences (December
    2014). Retrieved July 1, 2016 from http://ento.psu.edu/extension/factsheets/phorid-flies
12. Mann, Rajinder S.. Kaufmann, Philip E.. Butler, Jerry F., “Lutzomyia Shannoni” University
    of Florida, Entomology and Nematology Department. (Reviewed February 2015).
    Retrieved July 1, 2016 from
    http://entnemdept.ufl.edu/creatures/misc/flies/Lutzomyia_shannoni.htm
13. “Parasites – Leishmaniasis.” Centers for Disease Control and Prevention (January 10, 2013).
    Retrieved July 1, 2016 from http://www.cdc.gov/parasites/leishmaniasis/gen_info/faqs.html
14. “Structural and Public Health Pests Flies (Drain Flies, Fruit Flies, Fungus Gnats)” Purdue
    University: Medical Entomology. 2008 Retrieved July 01, 2016 from
    http://articles.extension.org/pages/23626/structural-and-public-health-pests-flies-drain-flies-fruit-flies-fungus-gnats
15. Shovlin, Joseph P. O.D. “Can Eye Gnats Cause Infection?” (April 15, 2010). Retrieved
    July 1, 2016 from https://www.reviewofoptometry.com/article/can-eye-gnats-cause-infection
16. “Hessian Fly”. Purdue University Field Crops IPM. (2009) Retrieved July 1, 2016 from
    https://extension.entm.purdue.edu/fieldcropsipm/insects/hessianfly.php