What Are the Houseplant Gnats?
The term “houseplant gnats” refers to four types of microscopic flying insects: drain flies, fruit flies, phorid flies, and fungus gnats.
Drain flies and phorid flies commonly congregate near rubbish, drains, and sewers. Fruit flies are drawn to rotting fruits and vegetables, as well as open bottles of wine, sweet drinks, or vinegar. Fungus gnats are commonly found near houseplants sitting in moist soil.
Houseplants are lovely enhancements to add color to any room, but not when overrun with little flies. Here are four great ways to get rid of these critters – and stop them from coming back.
You might occasionally see miniature bugs fluttering in and around your houseplant pots, and these are likely to be fungus gnats.
4 Ways To Get Rid Of Houseplant Gnats
Generally, 3 to 4mm long with greyish brown bodies, these little bugs are magnetized to damp soil and rotting leaves, which illustrates why houseplants are a particular hotspot for the gnats.
Although they’re not destructive, their existence is usually a nuisance, and their exaggerated breeding routines mean it’s best to fight fungus gnats earlier rather than later.
Adult houseplant gnats live about one week and lay up to 300 eggs in humid soil. Within four to six days, tiny larvae turn up and feed on plant roots.
The transformation stage lasts between three to four days before adults leave the soil and the next generation will start.
The full life cycle from egg to adult may be finished in three to four weeks, revolving around temperature.
The larvae mainly feed on dead roots and diverse decaying plant material, however, some species feed on soft plant growth – like seedling roots – which can be more of an issue.
Established plants are unlikely to be affected by fungus gnat larvae because of their well-developed root system, but it’s a good idea to keep healthy and infected plants apart from one another until the gnats clear out.
When bringing any fresh houseplant home, keep it in a unique room from your other plants for at least a few weeks while you wait to see if it is concealing unwelcome visitors.
If you spot insects on a plant, transfer the plant and its container elsewhere from your other plants, to prevent them from also being corrupted.
Although bugs are unavoidable in the realm of houseplants, you’re unlikely to want 300 fungus gnat eggs embedded in your soil.
And the good news is there are practical procedures you can take to rid your plants and yourself of the prospect of fungus gnats returning in large numbers.
Top Tips To Treat Fungus Gnats
A great place to start is to look at indoor plants regularly to ensure they are not over-watered, as this facilitates fungus gnats to breed and flourish.
You can often ward off houseplant gnats by giving plants a break in watering, but be extra wary with using this method on drought intolerant plants, as it could do more harm than good.
Always inspecting plants will help you take action before a large community of gnats grows.
If you turn to other options for clearing your plants of gnats, start with your local garden center’s non-pesticide control section.
Beneficial nematode species can eradicate fungus gnat larvae. They target pest types we don’t want to encounter in our soil, but will not hurt your soils or plant matter.
Add them to your soil and they will take out any burrowing fungus gnat larvae, as well as other pests.
Besides nematode species, you can use predatory mites such as Hypoaspis miles and Macrocheles robustus.
The mites will inhabit the soil and feed on the eggs and larvae of the fungus gnats, and while they control the pests in the soil, they will never harm the plant itself.
Alternatively, you can also try sticky traps, often one of the most effective and easy-to-use methods of gnat control.
They resemble sticky notes, which can be placed horizontally on the surface of your plants’ soil or on metal holders above it.
The traps have a glue coating that captures adult gnats and fresh houseplant gnats just emerging from the soil. Be sure to keep replacing your traps as more flies stick to them to help clear them all away!
Sticky traps, unfortunately, don’t affect larvae still in the soil. So, to combat the burrowing pests, Pros suggest drenching the soil with neem oil.
Neem oil is a natural pesticide, pressed out of the seeds from neem trees, and has a long history of being used to control insects.
Although drenching the soil with neem oil will kill fungus gnats, it will leave other harmless insects that roam your houseplant untouched.
Diatomaceous Earth (DE)
Another method for killing fungus gnats is to apply diatomaceous earth (also known as DE) to the soil’s surface. Any gnats that try to fly into your houseplants will be trapped by this organic abrasive powder.
The powder should only be used on dry soil. To keep it dry, place a layer of sand on top of the potting soil and apply the DE above the sand. In this instance, you should water your plants from the bottom up.
I recommend using pesticides as a last resort because insects may develop resistance to them.