Mosquito Dunks
 

I've an outbreak of fungus gnats, so thought I would try mosquito dunks.

A few questions.

They don't dissolve, but instead little bits of "woodchip" seem to break off? I used 1/4 dunk in a bucket, but most of it didn't breakdown - is this normal?

How often do they need to be used?

Can you reuse the bit that stayed intact again?

How long do they need to take effect?

Those consist of pressed sawdust impregnated with bacterial spores. I don't know how long the spores/bacteria remain viable once they get good and wet. The mechanism is that larvae eat spores, which sprout in their gut, which kills the larvae.

I had a terrible outbreak after repotting my collection. I used a plastic water bottle added a piece of the dunk and tepid water. I sprinkled the mixture on the orchid bark after every watering and after several weeks the gnats were gone. Easy Peasy just requires patience.

Put an entire dunk in a bottle containing 4-5 liters of plain water and let it sit for a couple of days, then just water with it, and refill the bottle.after a couple of weeks of using that water for irrigation, they should be all gone.

If you need a LOT of dunks, you can order off the company's website. It is cheaper, and they have larger quantities. Not thinking gnats here, but mosquitos. We use them on ponding in the woods. Doesn't hurt the frogs just the mosquitos.

Also to note, they do build natural colonies in the soil over time, so not sure if it does that in pots, but good to hope for.