Has anybody tried using Mosquito Dunks to control fungus gnats?

14 years ago

I'm thinking about giving them a try. I don't know how to use them in a worm bin. Can I just toss it in the bin, or do I need to put it in a jar of water and pour some of the water in the bin?

Comments (3)

mr_ed
14 years ago
I have never used them myself but I know "Bacillus thuringienis israelensis", the active "ingredient" in Mosquito Dunks will kill fungus gnat larva it is comes in contact with them so I see no reason why it should not control a population in your bin. I would use 1/2 a dunk and soak it in the recommended amount of water and use this treated water to soak some bedding in and mix it into the bin. Fungus gnats like wet conditions so after application I would let the bin dry out on the surface to further discourage any remaining adult gnats to lay eggs back into the bin.

I had a gnat problem the first summer I had my bin. I think they started in the worm bin and quickly spread to all houseplants and then started swarming in the kitchen. I applied beneficial nematodes to some coco coir and used it to top dress all plants and dumped the rest into my bin. I have not had any fungus gnat problems since.

I believe Bentley is experimenting with dunks on his blog now and may have more/better info...

Here is a link that might be useful: Can Mosquito Dunks Kill Fungus Gnats and Fruit Flies?
sbryce_gw
Original Author
14 years ago
I put 1/4 of a mosquito dunk in a 2 liter bottle, and filled it about 2/3 full of water. I let it sit for two days. I poured some of the water into one of my bins. The next day I had a bunch of attempted escapes. The worms who are trying to escape are pale and bloated. So far it looks like the BTi is making the worms sick. Digging around in the bedding turned up a lot of worms that still look healthy. I was going to pour more BTi water into the bin, but I'll wait and see how the worms look over the next few days.
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sbryce_gw
Original Author
14 years ago
I found this on a site about fungus gnats:

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Gnatrol is only toxic to larvae for two days. Repeat applications, i.e. two or three applications at high rates, may be needed to provide effective control.

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which tells me two things: 1) To control fungus gnats with BTi, one would have to repeat applications every few days for a couple of weeks (or more, since you can't soak all of the bedding at once). 2) If the BTi is making the worms sick, they should be OK in a few days.