The study compared the efficacy of FourStar Briquets and VectoMax WSP, both are Bacillus thuringiensis subsp. israelensis and Bacillus sphaericus combination larvicides designed to provide longer control of mosquito larvae in closed systems such as catch basins. Both products proved equally effective at controlling mosquito larvae with an average 92% efficacy for each. Testing during cool wet summers proved to have control longer than indicated by the product label, while testing in hot dry summers showed control only to the stated efficacy of the product.
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