FourStar™ Briquets contain the proven active ingredients Bacillus sphaericus (B.S.P.H.) and Bacillus thuringiensis subspecies israelensis (BTI). The environmental advantages of active ingredients Bacillus sphaericus and Bacillus thuringiensis israelensis are well known, making microbial larvicides the material of choice in many situations. To enhance the performance and control duration, FourStar has developed patent pending Dual Action Release technology. This innovative technology regulates the release of microbials to the water surface and throughout the water column as the briquette slowly dissolves. BTI and B.S.P.H. are naturally occurring soil bacteria that have insecticidal activity on mosquitoes. These bacteria contain protein crystals which, when ingested by mosquito larvae, rupture the gut wall of the larvae, resulting in larval death.