Mosquito Dunks are safe around pets, fish, and wildlife when used as directed, since their only active ingredient is a naturally occurring soil bacterium. That bacterium targets the digestive system of mosquito larvae specifically, leaving animals, plants, and most other organisms in treated water unaffected.

What Makes Mosquito Dunks Different From a Chemical Pesticide?

Mosquito Dunks release Bti, short for Bacillus thuringiensis subspecies israelensis, as they float and slowly dissolve in standing water, and larvae die only after they ingest the bacterium. The Centers for Disease Control and Prevention states that Bti is not toxic to people and will not harm pets and other animals, aquatic life, or other insects such as honeybees.

Where Can Mosquito Dunks Be Placed Safely?

Floated in a birdbath, livestock trough, or ornamental pond, a single Mosquito Dunks tablet treats up to 100 square feet of surface water regardless of depth. Mosquito Dunks' own label states they are safe for use around people, pets, and wildlife, including drinking water for animals, and are harmless to fish, birds, frogs, and turtles.

Does the Bacterium Keep Working After It's Eaten?

Yes. Each Dunk continues releasing Bti for at least 30 days, and the CDC notes that Bti kills mosquito larvae only after they eat it rather than on contact, so new eggs laid in treated water are controlled before they mature into biting adults.

Is This Approved for Organic Gardens?

Mosquito Dunks' own label lists the product as approved for organic use, so a garden following organic practices can still treat standing water without stepping outside that standard. The same Bti formulation is registered with the Environmental Protection Agency, which the CDC cites as the basis for its safety review of Bti products.

Frequently Asked Questions

Can Mosquito Dunks be used in a pond with koi or goldfish?

Yes. The product's own label lists koi ponds among its intended uses and states Bti is harmless to fish.

Do Mosquito Dunks harm bees or other helpful insects?

No. The CDC lists honeybees specifically among the organisms Bti will not harm, since the bacterium only affects mosquito, black fly, and fungus gnat larvae that ingest it in water.

How often does a Dunk need replacing?

About every 30 days, or sooner if it has fully dissolved, since that is when the slow release of Bti runs out.

Can one Dunk be split for smaller containers?

Yes. The label notes it can be broken into smaller pieces for use in small containers such as a plant saucer or gutter, with each piece still releasing Bti as it dissolves.

Are unused Dunks safe to store for next season?

Yes. Kept dry, an unused Dunk keeps its potency indefinitely, so extras bought for one season remain useful the next.