I think mosquitoes and fungus gnats is all it kills? Try and see?
The most effective larvae killer we've found! For outdoor use, place Mosquito Dunks in ponds or standing water and it's active ingredient, BTI (Bacillus thuringiensis subspecies israaelenses) kills mosquito, black fly and thrip larvae for 30 days or more, avoiding annoying mature insects.
While floating they slowly release a long term biological larvacide killing the larvae before they hatch into adults. Will not effect fish, plants, people or wildlife. Use in birdbaths, flowerpots, rain barrels and gutters. Use one dunk per 100 square feet of water surface.
For indoor gardening use, Mosquito Dunks are perfect for eliminating the new variety of thrips plaguing the US as this particular bacteria eats anything in a larval stage. It may take a couple of weeks, but it does work.
Hydroponics Application: Place an appropriate portion of a Mosquito Dunk into a nylon sock (helps prevent solid debris) and drop into reservoir. If your infestation is overwhelming, after 24 hours, knead the Dunk slightly to help intensify bacteria saturation - this will shorten the lifespan of the Dunk.
Soil and Soilless Plants: Put a Mosquito Dunk into a nylon sock and soak in water for a few days - Use 1/2 of the innoculated water to thoroughly water plants. Refill container with water and continue to soak same Dunk and repeat watering process. Replace Dunk after 30 days if needed.
Comes in package of 6 Mosquito Dunks. Alternate wetting and drying will not reduce it's effectiveness. Disks may be broken into smaller pieces or secured within nylon sock to avoid being washed away.
So just buy the discs & crumble on top of the soil?
Do you have to put enough to cover the whole soil or just about half?
How often should you add more?
It WILL work, on the larvae in the soil, but it won't kill adults flying around.
It takes a while to kill all the hatching ones, but once you get this product in your grow, eventually, they won't come back... give it a few weeks...