Spheratax SPH 50G WSP 40lbKill Mosquito Larvae Before They Develop Into Harmful, Biting Adults! Spheratax SPH 50G Granules provide powerful selective mosquito control when placed where mosquitoes breed. This microbial larvicide contains Bacillus sphaericus spores, a naturally occurring beneficial organism. When used as directed and introduced to organic rich water sites, spores are consumed by mosquito larvae. Once ingested, the bacteria spores release toxins into the guts of