Have you noticed tiny black insects flitting around your houseplants or near your sinks? You're most likely dealing with an invasion of fungus gnats in the home or, worse still, the dreaded drain flies. These little pests have an annoying habit of colonising our living spaces as soon as the warm weather arrives or damp sets in.
Faced with this irritating situation, one question often comes up: are drain flies dangerous? Rest assured, these insects don't bite and don't transmit serious diseases to humans. However, they happily carry bacteria, harm the health of your plants and spoil the look of your home.
If you're fed up with seeing these insects, knowing how to get rid of fungus gnats becomes the top priority. Whether you're after an effective fungus gnat treatment or a natural way to get rid of drain flies, you're in the right place. Discover our complete guide to wiping out these invaders and keeping your home clean for good.
Fungus gnats or drain flies: how to tell the difference?
To effectively get rid of the pests invading your home, you first need to know what you're dealing with. We tend to lump all these little insects together under the catch-all name "gnats", but the fungus gnat (sciarid fly) and the drain fly (moth fly) are two very different species that don't nest in the same place and don't cause the same damage.
Here's how to investigate at home to correctly identify your invader:
The fungus gnat and its larvae (sciarid flies)
If you see tiny black gnats rising in a cloud as soon as you touch or water your houseplants, there's no doubt about it: you're dealing with fungus gnats. Drawn to decomposing organic matter, these insects love to lay their eggs in constantly damp compost or poorly drained potting mix.
The real problem isn't the adults, but the fungus gnat larvae. Hidden in the soil, these translucent, voracious larvae feed on the fine root hairs of your plants. Compost that's too wet, combined with a mild indoor temperature, speeds up their life cycle, quickly turning your plant pots into a gnat factory. Over time, the larvae weaken the plant, slow its growth and can even kill it if nothing is done.
The drain fly or moth fly
If, on the other hand, your gnats have a stockier body, hairy, heart-shaped wings (resembling tiny moths) and they linger on the walls of your shower, bath or kitchen sink, then you're looking at the drain fly, also known as the moth fly.
Unlike its plant-dwelling cousin, the drain fly lays its eggs directly in the biological film (the "biofilm") lining the inside of your pipes. This thin, slimy layer, formed from a build-up of food residue, grease, soap and hair, is the ideal larder for their larvae. They love stagnant water and the darkness of pipes, and take advantage of the slightest opening to come out and colonise your wet rooms.
How to get rid of fungus gnats in compost?
If your plant pots have become the headquarters of these pests, don't panic. To successfully get rid of fungus gnats, you need to act on two fronts: eliminate the flying adults and destroy the larvae hidden in the soil.
Here are the most effective and environmentally friendly solutions for a natural fungus gnat treatment, without filling your home with toxic chemicals.
Natural remedies to wipe out larvae and adults
- Nematodes (the most effective biological control): For a radical treatment, using nematodes against fungus gnats is without doubt the best solution on the market. Nematodes (usually the Steinernema feltiae species) are microscopic worms invisible to the naked eye. You simply dilute them in your watering can. Once in the soil, they actively hunt down the fungus gnat larvae, enter them and parasitise them until they die. Completely harmless to people, pets and plants, they disappear naturally once there are no more larvae to feed on.
- Coffee grounds (the old wives' remedy): If you're after a cheap, instant solution, fungus gnats and coffee grounds get along nicely... in your favour! Coffee grounds act as a natural repellent thanks to their strong smell and texture. Let them dry out thoroughly (very important to avoid mould), then scatter them in a thin layer over the surface of the compost. Not only does this deter the egg-laying females, it also gives your plant a light feed.
- Bottom watering (the free mechanical method): Since fungus gnats absolutely need a damp surface to lay their eggs, change the way you water. Pour the water straight into the saucer or reservoir for a few weeks. This keeps the top of the pot completely dry, instantly breaking the gnats' breeding cycle.
Should you use a conventional insecticide?
Faced with a large infestation, you're sometimes tempted to rush out and buy a fungus gnat spray from the shop. However, these chemical products saturate the air in your living room or bedroom with toxic molecules and often only solve the problem temporarily. Always go for the natural and biological alternatives above, or use yellow sticky traps to catch the adults as a complement.
Note: Once the treatments have been applied, the most important thing is to stop the residual damp from your plants attracting new invaders from outside. Further down, we'll see how to secure your windows for the long term.
Drain flies: a natural treatment to clean your pipes
If your flies aren't coming from your plants but escaping from your sinks, basin or shower plughole, you need to change targets. To get rid of drain flies, insecticide sprays will be of no use to you: the heart of the problem lies inside the plumbing itself.
To clean your pipes deeply and dislodge the larvae, there's no need to resort to corrosive chemicals that damage your pipework and pollute groundwater. There's a natural drain fly treatment that's highly effective, cheap and eco-friendly, and that you can do yourself.
The natural recipe to disinfect your traps
To destroy the organic film where the eggs and larvae of the drain fly nest, apply this simple method once a week until they've completely gone:
- The heat shock: Start by pouring a kettle of boiling water straight down the drain to soften the grease and eliminate some of the larvae at the surface.
- The fizzing reaction: Then pour in two tablespoons of bicarbonate of soda, followed by a large glass of white vinegar. The chemical reaction will foam intensely: this is completely normal, and the foam mechanically lifts away the residue caked onto the pipe walls.
- The resting time: Leave the mixture to work for at least 30 minutes (ideally do this in the evening before bed so it works overnight).
- The rinse: Rinse again generously with boiling water.
The crucial importance of drying out
Cleaning the pipes removes the breeding ground, but the drain fly remains irresistibly drawn to the smell of stagnant damp and water. To get rid of these insects for good, the only biological solution is to drastically reduce the humidity in your wet rooms. It then becomes essential to ventilate your kitchen and bathroom as much as possible.
But how do you throw your windows wide open to let the damp out without turning your home into a hotel for mosquitoes and flies? That's exactly what we'll look at next.
How to prevent them appearing and protect your home for good?
Have you cleaned the compost of your plants and disinfected your pipes? That's an excellent start. However, the risk of them coming back is high. Gnats, flies and mosquitoes have a highly developed sense of smell: the residual damp from a shower or the fresh soil of a houseplant will always attract them from outside.
To break this vicious circle, you need to change a few habits and, above all, secure the entry points to your home.
1. Fit a Moskera magnetic fly screen
To get rid of damp in the kitchen and bathroom for good, or to dry out the surface of your plants' compost, all the experts agree: you need to ventilate daily. But throwing your windows wide open in summer or autumn often means opening the door to every pest in the neighbourhood.
The ideal solution? Fit an impassable physical barrier. Moskera magnetic fly screens were designed specifically to solve this problem, without the drawbacks of traditional systems:
- Ventilate with complete peace of mind: You can open your wet rooms and living room for hours to let the damp out. By fitting your openings with a magnetic fly screen for windows, the ultra-fine mesh blocks even the smallest insects from outside (fungus gnats, tiger mosquitoes, flies), while letting fresh air flow through perfectly.
- No DIY, no tools: Unlike classic roller systems that require drilling into your frames, the Moskera fly screen fits in minutes using adhesive strips and high-performance magnets. Whether you need to fit a fly screen for doors to protect an entrance, or a large-format solution to secure a fly screen for patio doors, our system adapts without damaging your frames. It's the perfect solution for homeowners and renters alike.
- Smooth, automatic passage: Thanks to the magnetic central closure, the mesh opens with a simple gesture when you need to step outside (balcony, terrace, garden) and closes instantly and tightly behind you, leaving no gap for invaders.
Investing in a Moskera screen means guaranteeing yourself permanent comfort at home and lasting savings on insecticides and other chemicals.
2. Water your houseplants less often
To starve out the future fungus gnat larvae, follow the golden rule: let the top 2 to 3 centimetres of compost dry out before watering again. Also remember to empty the saucers under your pots systematically, a quarter of an hour after watering. If water sits there, the gnats are guaranteed to return.
3. Maintain your pipes and traps regularly
Don't let the biological film settle back into your pipes. Get into the habit of pouring a coffee residue or your bicarbonate-and-vinegar mix into the household drains once every two weeks, even if you can't see a single insect. Preventive maintenance is ten times more effective than a shock treatment.
4. Seal cracks and worn sealant
Drain flies love darkness and damp crevices. Inspect the silicone sealant around your bath, sink and shower tray. If the sealant is cracked, peeling or showing black mould spots, remove it and apply a fresh, watertight seal to eliminate these potential hideouts.
Protect your home today!
Don't let the heat and the insects ruin your life. With Moskera magnetic fly screens, keep your bathroom and kitchen free of flies, mosquitoes and moths for good.
