Recognizing the Signs of a Fungus Gnat Infestation

A fungus gnat can cause a lot of damage to plants by spreading plant disease. They lay hundreds of eggs in the soil, which hatch into larvae in only a week and cause damage by eating plant roots. This can kill or stunt the growth of plants.  If you want to avoid the damage and destruction that these critters cause, it's a good idea to be able to recognize the signs of an infestation, as well as the insect itself.

Identifying the Insect

Search for the insect. Fungal gnats resemble small flies and are about 1/16 to 1/8 inch long. Look to see what color the insect exhibits. Fungal gnats tend to have dark-colored bodies. If the legs of the insect are long, skinny, and look like a mosquito's legs, you may have an infestation of fungal gnats. The wings are another indicator. Look at the insect's wings and see if they have clear to light gray wings with a Y-shaped vein on each one.  

Examine Plants

Look over your plants to see if they have fungal gnats. It is common for these pests to consume younger plants. It’s also important to realize that theses pests prefer moisture, which is why they are usually more of a problem in greenhouses or with indoor plants than outdoor plants.  

Fungal gnats also leave behind slime trails, so this is another good clue that you may have an infestation of these pests. These trails are left behind by fungal gnat larvae. Unfortunately, the slime trails compound a pest problem because they also attract slugs and snails. However, a large accumulation of these critters is a sign that a plant has been infested by fungal gnats.

Fungal gnats tend to stay close to the ground, so it's easy to find an infestation if you look close enough. Examine the leaves and the soil when looking for the pests. Although these insects are not harmful to people, they can be a problem because they can spread diseases that may damage your houseplants.

Although fungal gnats can cause damage to plants and may even stunt growth, they do not kill them. These pests like moist soil because this is where they lay their eggs.

Fungal gnats look similar to mosquitoes, but are smaller in size and don't fly around as much as mosquitoes. The adults are not usually problematic - the larvae laid in the soil is what you have to watch out for because they eat the plant's roots and can cause some damage.

So how do you get rid of a fungal gnat infestation? One product uses bacteria to kill the insects. The advantage of this solution is that you can kill the fungal gnats without hurting your plants. If you don't want to use bacteria to kill the gnats, try sticky traps or parasitic nematodes. You can also apply a pesticide to the plant to get rid of the pests.