Gnats Around the Litter Box? Where They Breed and How to Trap Them
Tiny flies near the box mean something damp and organic is rotting nearby. Dry it out, clean the box and catch the adults with sticky traps.
By Jamilur Rahman Updated November 5, 2026 · 6 min read
- Time
- 30 min
- Cost
- Under $20
- Difficulty
- Easy
In this guide
Quick answer
If your litter box has gnats, the likely reason is damp litter, an open waste bin or a nearby drain that feeds the tiny flies. Scoop daily, replace wet or clumped litter, wash and fully dry the box and empty the bin. Then hang yellow sticky traps out of your cat's reach to catch the adults while the source dries out.
Free fix vs. permanent fix
Dry out and deep clean the box
- Throw out wet or clumped litter and wash the box with hot water and unscented dish soap
- Dry the box fully before you refill it
- Empty the trash and the scooped-litter bin, and take the bag outside
- Check the nearby drain, plant pots and food bowls for a damp source
How long it lasts: Works as long as the damp source stays gone. The gnats return if the litter stays wet or a drain keeps feeding them.
Yellow sticky gnat traps
Cleaning removes what the gnats breed in, but the adults already flying will lay more eggs. Yellow sticky cards catch them in the air, which breaks the cycle while the area dries. Hang them high, out of your cat's reach, and the problem stays gone.
How long it lasts: Each card works for a few weeks, until it is covered with insects.
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What you'll need
-
Rubber gloves
For emptying and washing the box
You have it -
Unscented dish soap
Strong scents can put some cats off the box
You have it -
Lidded waste bin
For scooped litter, emptied every day
You have it - Our pick Illustration
Yellow sticky gnat traps
Place them where the cat cannot touch them
- Illustration
Lidded litter disposal pail
A tighter seal than an ordinary trash can
Why it happens
Damp litter
Urine-soaked clumps left sitting hold moisture. Fungus gnats lay eggs in damp, rotting organic material, and plant-based litters can stay wet or grow mold if you do not scoop.
A drain close to the box
Drain flies look like tiny fuzzy moths and breed in the slime inside floor and sink drains. A litter box in a bathroom or laundry room is often next to one.
An open waste bin
Scooped litter in an open bin ferments and draws flies. So do wet food leftovers in a bowl beside the box.
Soggy plant soil in the same room
Overwatered houseplants are the classic breeding ground for fungus gnats, and the adults fly over to the box.
Try this first (free)
Do these in order, starting with the simplest.
-
1. Look for where the damp is
Check under the box, around the bin, near drains and in plant pots. Gnats gather where the damp is.
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2. Throw out wet litter and wash the box
Tool used: Unscented dish soapScoop all the clumps. If the bottom layer is damp, empty the whole box. Wash it with hot water and unscented dish soap, rinse, then dry it completely before refilling.
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3. Seal the waste
Tool used: Lidded waste binTie scooped litter in a bag and put it in a lidded bin, or take it outside every day. An open bin is a feeding ground for flies.
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4. Dry out the area
Wipe up spills, fix drips and let plant soil dry an inch or two down between waterings. Run a fan or a dehumidifier in a damp laundry room.
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5. Clean the nearby drain
Scrub the slime from the drain opening with a brush and flush it with very hot tap water. Do not pour boiling water into a PVC drain.
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6. Catch the adults with sticky traps
Tool used: Yellow sticky gnat trapsHang or stake yellow sticky cards a few feet from the box, up high and out of reach of pets and children. Check them weekly and replace them when covered.
IllustrationCheck price on AmazonTool for this step
Yellow sticky gnat traps · Place them where the cat cannot touch them
When free fixes aren't enough
Cleaning removes the breeding ground, but adult gnats live about a week or two and keep laying eggs, so a few survivors can restart the cycle. Traps close that gap. If you still see gnats after two weeks of a dry, clean box, look for a hidden source: a leaking pipe, damp carpet, a forgotten bag of litter or a clogged drain. Do not spray insecticide near the box. Some bug killers, especially ones containing permethrin, are toxic to cats. If your cat seems unwell after exposure to any spray, call your vet.
Buy the fix
Still stuck after the free fixes? These are the products we would look at.
| Pick | Product | Fixes | Who it's for | Buy |
|---|---|---|---|---|
| Best pick | Yellow sticky gnat traps | adult gnats flying around the box | Anyone with gnats flying now, while the damp source dries out. | Check price |
| Upgrade pick | Lidded litter disposal pail | scooped litter that feeds flies and smells | Households where gnats keep coming back around the waste. | Check price |
Yellow sticky gnat traps
Fixes: adult gnats flying around the box
Look for: Yellow cards, the color gnats are drawn to; Stakes or a hanging clip, so you can place them high; Glue only, with no added insecticide.
- Who it's for
- Anyone with gnats flying now, while the damp source dries out.
- Honest downside
- Your cat or dog climbs on shelves or sniffs everything. Sticky glue can stick to fur and paws, so use a spot they cannot reach.
Lidded litter disposal pail
Fixes: scooped litter that feeds flies and smells
Look for: A tight lid that closes by foot or by hand; Holds at least a day of scoops without overflowing; Takes standard trash bags.
- Who it's for
- Households where gnats keep coming back around the waste.
- Honest downside
- You can carry scooped litter outside every day. A lidded can you already own does the same job.
As an Amazon Associate I earn from qualifying purchases. We don't show prices because they change, so use the button to see today's price.
How we picked: How we picked: this page is based on pest-control guides for fungus gnats and drain flies, pet-safety advice on insecticides, and what cat owners report in reviews of sticky traps. We do not test products by hand.
Which gnat do you have?
- Fungus gnats: small, dark and weak fliers that hover near damp soil, wet litter and plant pots.
- Drain flies: fuzzy and moth-like, resting on walls near sinks and floor drains.
- Fruit flies: tan, hovering around food bowls, trash and ripe fruit.
The fix is the same for all three: remove the damp, rotting source and trap what is left.
Keep the box dry for good
- Scoop every day, and fully change the litter on a regular schedule.
- Keep the box away from drains and plants.
- Seal scooped litter before it goes in the bin.
- Fix leaks and dry spills at once.
What to skip
Bug spray and bleach around the box
Insecticides can poison cats, and strong fumes build up in a small room. Stick to drying, soap, a tight lid and sticky traps.
Frequently asked questions
Why does my cat litter have gnats?
Are gnats near the litter box harmful to my cat?
Do I need to change all the litter?
How long until the gnats go away?
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