Soil applications ofBeauveria bassianawere effective in controlling first- and second-generationLeptinotarsa decemlineatapupae, with a 74% reduction of the first generation and a 77% reduction of the second. The applications reduced adult emergence from pupation and increased postemergence mycosis. Conidia were superior to blastospores in reducing emergence, but produced no significant difference in postemergence mycosis. Soil isolations showed half the inocula present after 2 weeks.