Fungus Gnats are small, mostly harmless, bugs that tend to show up in homes in the mid-winter months. Even though these bugs are not dangerous, they are annoying and unsightly. Our team at Environmental Pest Management has had lots of experience ridding homes of pests and we created an easy guide to these critters and how to get rid of them.

If you’re an avid gardener and love your flowers and houseplants as much as you love your pets, you will want to know about fungus gnat larvae and how to kill gnats. Fungus gnats are a minor houseplant pest that is most noticeable as swarms flying around your home and plants.

They are generally harmless to humans, although they are certainly infuriating if they are flying around your face, eyes, and ears. However, they can be devastating for your plants. Here at Environmental Pest Management, we have collected some info about fungus gnats and some tips to eliminate and prevent gnat infestations.

What Are Fungus Gnats

Fungus gnats are tiny, fruit fly-sized insects that are between 1/16 and ⅛ of an inch in length, making them very difficult to see until they are swarmed. They have grayish-black bodies and transparent wings, although they typically stay close to the ground and plant soil. Fungus gnat larvae are hairless and legless with transparent bodies and black-colored heads.

Their life cycle only spans a couple of weeks, but they can cause a lot of damage to your houseplants in that time. Your houseplant is their habitat and food source. At the rate that they breed, the damage can be cumulative and continuous.

Typically found in areas with high humidity or in overwatered houseplants, fungus gnats make their home in the moist soil. Adults lay eggs (up to 200 or more at a time) on the organic matter near the soil surface. Within three days, fungus gnat larvae hatch. The larvae then dig down into the soil to feed on other plant material, fungi, and your plant’s roots and root hairs before resurfacing as adults and repeating the process.

Also Read: Secret Bug Breeding Grounds in Your Home This Winter


Fungus Gnat Damage

These insects do not bite, nor do they spread disease to humans like some other pests. However, they can be extremely harmful and even fatal to your beloved houseplants. Because the fungus gnat larvae feed on the organic material and roots in the soil, they will stunt your plant’s growth. If the roots suffer extensive damage, the plant will begin to wilt and then die.

Fungus gnat larvae also can carry plant pathogens which can disease a mature plant and kill your seedlings. If the lower leaves turn yellow and drop, or new buds are delayed or stunted in their development, it’s a good sign that you have fungus gnats.

Besides causing damage to your houseplants, fungus gnat infestations can be an extreme nuisance in your home, workplace, or any indoor space. They are not strong fliers, but they will swarm around the plant and near drainage holes.

Plants that fungus gnats most commonly infest and feed on are:

  • African Violets
  • Alfalfa
  • Carnation
  • Clover
  • Corn
  • Cucumbers
  • Easter Lilies
  • Geraniums
  • Lettuce
  • Nasturtium
  • Peace Lilies
  • Peppers
  • Poinsettias
  • Potatoes
  • Spider Plants
  • Soybeans
  • Wandering Jew
  • Wheat


Fungus Gnat Elimination

So how do you get rid of these pesky critters? Consistency and traps are the best methods for how to kill gnats. At the speed which fungus gnats reproduce, it’s essential to replace traps frequently. There are several types of traps you can choose:

Sticky CardsPurchasable at your local houseware or garden store, these yellow note cards are covered in a sticky adhesive that traps gnats when they land on it. Gnats are said to be attracted to the color yellow, luring them to your trap. For best results, cut some into small squares and litter them on top of the soil or place them on skewers around the plant. Replace them regularly.

Cider Vinegar Traps

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You can make these traps right at home! Use a small container to mix equal amounts of water and apple cider vinegar. Add a little bit of liquid dish soap, then stir. Place the container either on top of the plant soil or near the base of the pot. Keep an eye on it and replace the liquid as needed.

Diatomaceous Earth

Diatomaceous earth is a soft, crumbly, organic powder made from the fossil remains of diatoms. It’s available at home and gardening centers and is a natural and safe bug-killer.

Apply by dusting it onto dry soil only and scatter it around the inner edges of your pot and at the plant base. DE (diatomaceous earth) will stick to the gnats inhabiting your plant and dehydrate and paralyze them.

Avoid getting the soil of the plant wet after you have applied DE. If the powder becomes wet, it will dissolve and become useless. To keep the powder from getting wet, we recommend watering the plant from the pot bottom.

Fly Paper

Long, ribbon-like paper covered in a sticky, insect-catching adhesive is another surefire way to trap gnats. Farmers commonly use flypaper, but it might not be the prettiest wall fixture in your house. However, if But, if swarms of fungus gnats plague you, flypaper is certain to do the job.

BT Thuricide Spray

Environmental Pest Management often recommends an easy to use spray called BT Thuricide. This spray contains a microbe that kills the larvae of a fungus gnat which in turn eliminates the problem before it can grow.

This pesticide is safe for beneficial animals such as birds or honeybees and safe for use on food gardens so you can use it both indoor and outdoor up until the day of harvest.

Also Read:  Natural Home Remedies to Get Rid of Ants


How To Prevent Fungus Gnats

There are a couple of things you can do to keep fungus gnats from invading your home and infesting your indoor plants. These tips will also help prevent a gnat population from reappearing after you’ve eliminated them.

  • Maintain drier soil by watering less frequently, especially in winter
  • Use mosquito dunks
  • Layer your indoor plants’ topsoil with sand

Be consistent with maintaining your traps and prevention methods. The problem is already out of hand if there are swarms of fungus gnats flying around your home. Your plant may be suffering from a gnat infestation even without swarms, so it is essential to examine your plants for signs of gnats and continue pest control.

Get Expert Assistance

If you’re struggling with fungus gnats, let Environmental Pest Management help you take care of your pest problems. We use environmentally friendly methods to get rid of unwanted critters, no matter how small. Contact us today, and one of our friendly staff members will help you right away. Before long, the gnats in your home will be nothing more than a memory.