Bacillus sphaericus is a bacterium that is specifically pathogenic to mosquitoes. The current study investigated the particle behavior of a spray-dried technical concentrate and a water-dispersible granule (WDG) formulation of B. sphaericus in an aqueous column. The objective was to determine the distributional behavior (minus any extraneous environmental factors) of B. sphaericus within a water column over time. Studies showed a homogenous distribution of particles over a 16-h period for the technical concentrate and WDG. The particle behavior of the WDG formulation also showed homogenous distribution of particles at 64 and 128 h. These results show that declines in particle availability in the field may not be due to the bacterium itself or to the WDG formulation.