What the Heck is a Mosquito Dunk?

Mosquito Dunks are little 'donuts' containing a bacteria called Bti which is toxic to mosquito larvae. The idea is to place these dunks in a shallow stagnant water body where mosquitoes lay their eggs, such as an old tire, birdbath, or even a coffee can partially filled with water. As the material in the dunk dissolves, it becomes a food source for the mosquito larvae. Over time, the Bti infects the larvae and it dies.

Effectiveness - I can personally attest that this stuff works, but it is important to remember that this is a food source. If someone tries to put a dunk in a pond that already has plenty of good muck for larvae to eat, it probably won't work very well.

Toxicity - These are safe to use around fish and wildlife (per the manufacturer). The Bti has undergone a lot of toxicity testing, and all the inert ingredients are all food grade and medical grade.