Mosquito Dunks are the better fit for a pond or rain barrel, since each dunk releases its larvicide gradually over 30 days or more of standing water. Mosquito Bits release their active ingredient all at once, so they suit a quick knockdown in soil or a container you'll refill soon, such as a saucer under a planter, rather than water that sits for weeks at a time.
What Do Mosquito Dunks and Mosquito Bits Have in Common?
Both Mosquito Dunks and Mosquito Bits use the same active ingredient: Bti, short for Bacillus thuringiensis subspecies israelensis, a naturally occurring bacterium that kills mosquito larvae when they eat it. Both are manufactured by Summit, and both are labelled as non-toxic to pets, fish, wildlife, and humans when used as directed.
What's the Difference Between a Dunk and a Bit?
A Mosquito Dunk is a solid, donut-shaped tablet that floats on the water's surface and releases its Bti gradually, lasting 30 days or more per dunk according to its product page. Mosquito Bits are loose granules that release their Bti all at once when they're wetted, starting to kill larvae within minutes and needing reapplication every 7 to 14 days for ongoing control.
Why Are Mosquito Dunks Better Suited to a Pond or Rain Barrel?
A pond or rain barrel holds standing water for weeks at a time, which matches how a Mosquito Dunk is designed to work: one dunk treats up to 100 square feet of surface water and keeps releasing Bti over the full month rather than needing to be reapplied every week or two. Mosquito Bits are built for the opposite situation, where the water or soil is refreshed often enough that a slower-release tablet wouldn't make sense.
Does Urban Nature Store Carry Mosquito Bits?
Urban Nature Store carries Mosquito Dunks in 2-pack, 6-pack, 20-pack, and 100-pack sizes, but doesn't currently list Mosquito Bits. For a pond or rain barrel, that isn't a drawback, since Dunks are the product built for standing water in the first place.
Which Pack Size Do You Need?
A single Mosquito Dunk covers 100 square feet of surface water, so a small rain barrel or decorative pond typically needs only one dunk broken to size, while a larger koi pond or multiple rain barrels around a property can call for the 20-pack or 100-pack to keep every container treated through the season.
Frequently Asked Questions
Are Mosquito Dunks Safe for Fish in a Pond?
Yes. The product's page states that Mosquito Dunks are non-toxic to fish, and that Bti is registered by the EPA for use in fish habitats and animal watering troughs.
How Long Does One Mosquito Dunk Last in a Rain Barrel?
30 days or more per dunk, according to its product page, which is long enough to cover most of a rainy season between replacements.
Can I Break a Mosquito Dunk Into Smaller Pieces for a Small Container?
Yes. The product's page states that a dunk can be broken into smaller pieces to treat smaller containers such as flower pots or gutters.
Is Bti Harmful to Pets That Drink From a Treated Rain Barrel?
No. The product's page states that Bti is non-toxic to pets and that a dog eating an entire dunk isn't adversely affected.
How Much Does a 20-Pack of Mosquito Dunks Cost?
$36.95 CAD, which works out to roughly $1.85 per dunk at that pack size.
