How to Get Rid of Gnats in Houseplants (Quick & Easy)
Indoor plants are extremely popular because they brighten up indoor spaces, are known to have mood-boosting qualities, help keep the air in your house fresh, and are an attractive component of many interior designs. They’re also a great option for people with little outdoor space and are usually quite easy to care for, but there is one little thing that many owners of houseplants would rather do without: gnats.
Gnats, also commonly known as fungus gnats, are small flying insects about the size of fruit flies that live and breed in the moist soil of potted household plants, feeding on fungus in the soil and rotting root material.
Usually, it will be the adult gnats that you notice first, harmlessly flying around your plants or gathering by a nearby window. But it’s the younger gnats, those still living and feeding in the soil as larvae, that are the most damaging to your plants.
Gnats or fruit flies?
Fungus gnats are small, black mosquito-like flies that are often mistaken for fruit flies. Despite their similar appearance, gnats and fruit flies are an entirely different insect.
The easiest way to tell them apart is to consider where you see them. Gnats live and breed in the soil and will usually be found flying around and crawling over the soil of your houseplants. On the other hand, fruit flies will be found flying around any fruit you have out, the garbage disposal system, or the kitchen waste bin.
How do gnats get into your houseplants?
To understand this, it’s important to learn about the gnat’s lifecycle. Adult fungus gnats will lay between 200-300 eggs in rich, moist soil. Within 5-6 days, the eggs hatch, and tiny white larvae feed on fungus and plant roots in the soil for about 2 weeks before emerging from the soil to start the breeding process again.
Adult gnats live for about 1 week, and their entire life cycle from egg to death takes just 3-4 weeks. Thus, it is entirely possible to have multiple generations of gnats, in all their life stages, living in and around the soil of your houseplants at the same time.
Gnat eggs and lava are extremely small and exceedingly difficult to see with the naked eye. So, it is entirely possible that potted plants brought in from outside or newly purchased from a nursery can contain gnat eggs and larvae with little or no visible signs of infestation. Also, in their adult state, fungus gnats can simply fly in through an open door or window.
What will fungus gnats do to your houseplants?
Gnats feed on fungus and other organic material in the soil. This often includes the roots of your houseplants, particularly the new roots of seedlings. With each adult female laying up to 300 eggs, it is easy to see how a large gnat infestation can quickly take hold in your houseplants, and thousands of gnat larvae can soon be munching on your plants’ roots.
It is unlikely that gnats will kill your houseplants. Still, an infestation can certainly make them wilt, may cause them to turn yellow, and will almost certainly slow their growth, with seedlings, cuttings, and young plants being the most susceptible to damage.
How to get rid of fungus gnats
You can do several different things to get rid of fungus gnats and ensure that they don’t return to reinfest your houseplants in the future. These fall into three basic categories: prevention, removing the adult gnats, and targeting the larvae. To completely eradicate fungus gnats, it is likely that you will need to employ tactics from each category.
Eradicate the adult gnat flies
The adult gnat flies are much easier to see than the larvae and easier to kill off, and targeting the adults makes it possible to significantly affect the fungus gnats’ breeding and life cycles and reduce their impact on your houseplants.
Unfortunately, while getting rid of the flies is relatively easy, there will likely be a new batch that emerges from the soil to reproduce and lay more eggs within a few days. Thus, it can seem like a losing battle if you only target the adult flies. Still, your chances of completely eliminating the fungus gnats will increase if you employ several different approaches.
Featured image credit: MarcOliver_Artworks, Shutterstock