Lawn Diseases
Mosquitoes in the Yard: Four Days of Water Is All
Penn State: mosquitoes breed in any still water standing more than four days, and residential fogging is the least effective method and is not recommended.
Biological mosquito larvicide (Bti briquet)
Summit Mosquito Dunks, 6-Pack Review
★★★★★ 5/5
our editor rating how we score4.5/5 from 29,066 shoppers at Amazon — their number, not ours.
$8–$12
Typical price · One dunk treats 100 square feet of water surface and releases for up to 30 days
Affiliate links — see our disclosure. Commissions never influence verdicts.
The one mosquito product extension services actively recommend, and it works on the water rather than the air.
Our Verdict
This is the product Penn State points at when it tells you that residential fogging is the least effective method and not recommended. It does not touch adult mosquitoes at all — it kills larvae in standing water, which is where the problem is actually manufactured. The label backs the marketing on duration: dunks are formulated to release effective levels of Bt israelensis for a period of 30 days, at one dunk per 100 square feet of water. Its labelled sites are the honest picture of what this is for, and it is a long list of things people forget: flower pots and saucers, gutters, rain barrels, tree holes, bird baths, discarded tires, unused swimming pools, catch basins, water gardens and ponds. Two things nobody tells you. It is a biological product with an expiry — the label reads 'not for sale or use after' a date stamped six months from manufacture, so a tub bought two seasons ago is not the product you think it is. And in New York it may only be applied to contained water sources. Rated top of our list because it is the rare case where the extension recommendation, the label and the product all say the same thing.
✅ Pros
- Attacks larvae, which is where the extension guidance points
- Label-backed 30 days per application
- Bti does not affect mammals, birds or fish (Penn State)
- Long labelled site list covering the containers people forget
- Signal word CAUTION, and no pollinator problem — it is not a foliar spray
⚠️ Cons
- Does nothing to adult mosquitoes already flying
- Six-month shelf life from manufacture, printed on the label
- New York limits it to contained water sources
- One dunk per 100 sq ft — a real pond needs several
Product type
Biological mosquito larvicide (Bti briquet)
Active ingredient
Bacillus thuringiensis subsp. israelensis, Strain SUM-6218 — 10.31%
Price range
$8–$12
Coverage
One dunk treats 100 square feet of water surface and releases for up to 30 days
Best for
Standing water you cannot drain — ponds, rain barrels, blocked low spots, bird baths and the water garden
our editor rating
5 out of 5
Where our facts come from
Label read on EPA's label database
EPA Reg. No. 6218-87
We opened this product's accepted label on EPA's own Pesticide Product Label System — the strongest source available for what a product is registered to do.
What we found when we read it
Full label read 2026-08-08 on EPA PPLS. EPA Reg. No. 6218-87. Active is Bacillus thuringiensis subsp. israelensis, Strain SUM-6218, at 10.31%, with a stated potency of 722 Aedes aegypti Units per milligram — and the label's own caveat that the percent active ingredient does not indicate product performance because potency measurements are not federally standardized, which is why we do not compare this percentage against the granule's 2.86%. Signal word CAUTION. Duration is label-stated: formulated to release effective levels for a period of 30 days. Rate is one dunk per 100 square feet of water surface. TWO FACTS WORTH RECORDING because no listing carries them: the label prints 'Not for sale or use after' a date stamped six months after manufacture — this is a living biological and it expires — and 'May only be applied to contained water sources in the State of New York'. Labelled sites include flower pots and saucers, funeral urns, gutters, rain barrels, discarded tires, woodland pools, small marshes, lake perimeters, catch basins, storm drains, flood water retention ponds, water gardens and ponds, fish farms, bird baths, tree holes and unused swimming pools.
Where this page and the container disagree, the container wins — the label is the legal authority on rates and restrictions. How to read one yourself.
Where This Product Matters
Matched against each state's actual disease, weed and pest pressure.
New York
New York hub →⚖️ Both Bti products we stock carry a New York restriction printed on the label — the dunk may only be applied to contained water sources in the state, and the granule is limited to containerized waters with no outflow to the natural environment. Neither is a statewide ban; both stop you treating a pond or ditch that drains anywhere.
Common questions
Common Questions
How much does Summit Mosquito Dunks, 6-Pack cost?
Summit Mosquito Dunks, 6-Pack typically runs $8–$12, covering One dunk treats 100 square feet of water surface and releases for up to 30 days.
What does Summit Mosquito Dunks, 6-Pack treat?
Summit Mosquito Dunks, 6-Pack targets Mosquito larvae, Fungus gnat larvae.
What is the active ingredient in Summit Mosquito Dunks, 6-Pack?
Bacillus thuringiensis subsp. israelensis, Strain SUM-6218 — 10.31%, registered under EPA Reg. No. 6218-87.
What is the biggest downside of Summit Mosquito Dunks, 6-Pack?
Does nothing to adult mosquitoes already flying
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