An aerially applied flowable concentrate (FC) of Bacillus sphaericus Neide (isolate 2362) was evaluated against riceland mosquitoes using the Beecomist spray head. Application of the FC at 0.58 and 1.17 liter/ha in maturing rice fields resulted in a 48 hr mean posttreatment reduction of Anopheles quadrimaculatus of 71 and 82%, respectively. A significant reduction in larval populations one week posttreatment was also observed. Treatment rates of 0.29, 0.44, and 0.58 liter/ha in reflooded second crop rice fields resulted in 48 hr posttreatment reduction of Psorophora columbiae larvae of 50, 76 and 98% respectively.