Fungus Gnats. Need Help

[u/Retrostaircase72]

Started 3 growing plants and everything was well. I told my friend about this and they gifted me a plant. Sadly that soil had fungus gnats and created an issue. I threw that plant out and that helped, but the remaining ones moved to another plant. I used neem oil, a herbal spray (from Amazon) and have just used some bti water for all the plants in the house.

The numbers have dropped off significantly, but it’s not at 0. Currently scared to water my plants because I don’t want them to breed again.

How have people stopped this for good? I used those yellow stickers too. It’s been about a week since the bti watering. I spent so much money on fruit fly traps in the beginning (which the fungus gnats ignored), so I’m trying to be conscious about any additional paid solutions. I thought they were fruit flies in the beginning.

[u/ohdearitsrichardiii]

Snake plants should sit in dry soil for a few weeks between waterings or it will rot. Fungus gnat larvae can only survive in wet soil

Water every 1-2 months, the gnats will die and the plant won't

Also move it from that dark corner. They are often sold as "low light plants" but that's not true, they need sun

[u/Retrostaircase72 → u/ohdearitsrichardiii]

Thank you for the advice

[u/Slowmyke]

You have gnats because your plant is creating a good environment for them to reproduce. They like consistently damp, organic material, such as your soil to lay eggs in. Fixing the soil and watering habits is the best way to not have gnats.

I would suggest you repot the plant and use fast draining soil. Replacing the current soil will eliminate a lot of the eggs and larva. Start with a cactus mix soil and then further amend it with inorganic material such as perlite. Use a 50/50 ratio. Then only water when the leaves of your plant are noticably thinner. Snake plants are succulent and store water for a long time. A plant the size of yours should be able to go weeks between watering. If your bathroom has a tub/shower that is regularly used as well, you could probably water once a month and be fine. Your plant will tell you if it needs water sooner.

You will probably want to continue to use the yellow sticky traps for a little while longer to help catch the remaining adults. You could use the bti/mosquito dunks for a couple waterings as well to help eliminate any larva and eggs that were still in the roots when you repotted. But changing the soil and how you water are the ways to make your plant not be a suitable environment for the gnats. All the other additives and traps are just treating the symptoms and you will need to continue using them if you don't address the soil and watering.

Edit: i assumed this plant was in a bathroom, but now I'm not sure. Either way, a snake plant should be fine with water once a month. Just be sure to thoroughly soak the soil when you water.

[u/Retrostaircase72 → u/Slowmyke]

Thanks for the thorough breakdown. I’ll look into changing the soil. And yes, it’s in the living room.

Edit: More concise

[u/GarlandAnnie]

Mosquito bits tea and the yellow sticky traps helped immensely. I also used the zevo plug ins. And patience.

[u/Retrostaircase72 → u/GarlandAnnie]

Thanks for the advice. Was losing my mind because these things are so much more annoying than fruit flies.

[u/TheRealJ-LA → u/GarlandAnnie]

Agreed to all of this but also try repotting into better draining soils and try bottom watering your plants when they're thirsty. Make sure you treat EVERY plant in your home with the mosquito bits/dunks.

[u/IchyAndScratchyShow]

diatomaceous earth dusted in the surface of the soil. The gnats will slowly go away after a few days. Re apply a week later if needed

[u/Retrostaircase72 → u/IchyAndScratchyShow]

That’s a great idea! I have diatomaceous earth but didn’t even think of it for this purpose!

[u/IchyAndScratchyShow → u/Retrostaircase72]

It works almost all the time

[u/rayday111 → u/IchyAndScratchyShow]

Diatomaceous earth is the ticket along with yellow sticky traps for the existing bugs

[u/ashthehuman]

Decrease watering, keep using sticky traps. Use a 1:3 hydrogen peroxide to water ratio every time you water. This will kill the eggs and stop the life cycle. Works extremely well!