I’ve had it with those tiny black flies buzzing around my houseplants. If you’re here, that probably means that you are also desperate to learn how to kill fungus gnats. Recently, fungus gnats were swarming my peace lilies and making me feel like a failure as a plant parent. Then I found mosquito dunks and bits. They’re cheap, safe products that destroy gnat larvae and let your plants breathe easy again.
These critters aren’t just a slight bother. They can hurt your plants pretty badly by chowing down on roots. The good news? You don’t need fancy sprays or a big budget to fight back. Mosquito dunks and bits use a natural bacteria to take out the larvae, stopping the cycle before it spirals. Let’s cover some tips on how to get rid of fungus gnats to keep your indoor jungle pest-free.
Using mosquito bits and dunks can be considered a cornerstone of solid fungus gnat control. This is actually so simple you’ll wish you’d tried it sooner. With a few bucks and some know-how, you can send those gnats packing and get back to enjoying your plants.
What Are Fungus Gnats?
Fungus gnats are these tiny little dark flies that are about 1/8-inch long you see in your houseplant soil. They look like a little mini mosquito, since they have skinny legs and wings, but they are harmless to you and don’t bite at all. If you don't water your houseplants properly the soil can stay moist for too long which draws the gnats in. They can lay up to 200 eggs at a time in your damp soil. The larvae, which are little white worms with black heads, hatch in a few days and start munching on fungi and, yep, your plant roots, too. If you’ve got a bad infestation, you’ll probably see yellowing leaves or maybe even stunted growth, like I did with my poor monstera plant.
They thrive in overwatered potted plants or soil that doesn’t drain well, which is why my overzealous watering routine was basically rolling out the red carpet for them. These pests can explode in number if you don’t catch them early and use effective fungus gnat control. Knowing what you’re up against is half the battle.
The worst part, though? They’re not just annoying. They can weaken your plants if you let them run wild. That’s why hitting the larvae is key, and mosquito dunks and bits are going to be your secret weapon.
What Are Mosquito Dunks and Bits?
Mosquito dunks and bits are like the unsung heroes of pest control. They were originally made to kill mosquito larvae in ponds or birdbaths. They’re packed with a very special bacteria called Bacillus thuringiensis israelensis (Bti). This stuff is very deadly to mosquito and fungus gnat larvae, but it’s safe for humans, pets, and plants. I was even skeptical at first. How could something for mosquitoes help my indoor houseplants? But it turns out, fungus gnats are close cousins to mosquitoes, and Bti wipes them out by messing with their digestive system so they can’t eat and grow into adult insects.
Mosquito dunks are donut-shaped pucks that dissolve slowly in water, releasing Bti over time. Personally, I like these Summit Mosquito Dunk Tablets from Amazon. Mosquito bits are smaller, like cornmeal, and work faster when you sprinkle or soak them. These Summit Mosquito Bits from Amazon are my go-to.
Both are dirt-cheap. Bti is so selective it won’t harm your dog if they sniff around or your plants if you use it right. It’s like nature’s own pest control, and I’m all about it. They’re a game-changer for anyone who’s watched gnats take over their indoor jungle.
How to Use Mosquito Bits for Fungus Gnats
Using mosquito bits for fungus gnats is straightforward, but you’ve got to do it right to see results. Here’s how I tackled my infestation:
- Mix the “tea”: Grab a gallon of warm water and stir in 4 tablespoons of mosquito bits. Let it soak for 30 minutes. Warm water helps the Bti release faster. I use an old milk jug to make it easy.
- Strain the bits: Scoop out the granules (they float to the top) with a spoon or use a mesh bag to keep things tidy. You don’t want chunks clogging your watering can.
- Water your plants: Pour the Bti-infused water over the soil as you normally would, making sure it soaks in deep where the larvae live. I hit every pot in my house, even ones without gnats, just to be safe.
- Repeat weekly: Do this every week for 3-4 weeks to catch new larvae as they hatch. It takes me about a month to see the gnats vanish completely.
- Pro tip: Don’t let the tea sit longer than 48 hours, since it can start to smell funky, like old corn water. Fresh is best.
How to Use Mosquito Dunks for Fungus Gnats
Mosquito dunks for fungus gnats work a bit differently since they’re bigger and slower to dissolve. Here’s the step-by-step:
- Break it up: Take a dunk and crumble a quarter of it into a gallon of water. You don’t need the whole thing unless you’ve got a ton of plants. Wash your hands after handling.
- Soak overnight: Let it sit for at least 12 hours to release an effective dose of Bti. I leave mine in a bucket overnight to make sure it’s ready.
- Remove the dunk: Pull out the leftover pieces (you can reuse them for another batch). Stir the water to mix it well.
- Water thoroughly: Use the Bti water to drench your plant soil, hitting all the pots with gnats. Make sure it gets down to the roots where those larvae are hiding.
- Repeat every 7-10 days: Keep this up for 3-4 weeks to break the gnat life cycle. I noticed a big drop in gnats after the second round.
Continued Fungus Gnat Control
Once you’ve knocked out the gnats, you don’t want them coming back. Water houseplants lightly and let the top inch of soil dry out between waterings. Gnat eggs and larvae hate dry conditions. Pairing Bti with yellow sticky traps catches adult gnats and cuts the population faster. I use these sticky traps for gnats from Amazon and place traps in every houseplant pot. You can also use these Zevo flying insect traps from Amazon to catch fungus gnats and fruit flies.
Check your plants weekly for signs of gnats, like flies buzzing or larvae in the soil. If you spot them, hit the soil with another round of Bti water. Use pots with good drainage holes, and maybe mix in some perlite to keep things airy. I recommend bottom-watering your plants to keep the top soil dry, which helps a ton. Store your bits or dunks in a cool, dry spot so they stay effective for next time.
Fungus gnats can turn your plant haven into a buzzing nightmare, but mosquito dunks and bits are like a cheap, secret weapon that actually works. I was ready to give up on some of my plants until I tried this, and now they are thriving without a single fly in sight. Keep up the Bti routine, don’t overwater, and maybe throw in some sticky traps for good measure. You’ll be back to having nice plants instead of swatting gnats in no time.
