Two isolates ofMetarhizium anisopliae(Metschnikoff) Sorokin were tested against the sugarcane pestInopus rubriceps(Macquart) in separate field trials. Conidia were mixed with attapulgite and applied to soil at two rates by four different procedures. When conidia were applied in the planting drill at 8.5–13 × 1014per ha, concentrations of conidia exceeded 1 × 106g−1in soil soon after application and were maintained above the background level for at least 34 mo. Residual concentrations were not significantly greater than background level when the same amount of conidia was broadcast over the whole plot. Bioassays indicated that the isolate FI 161 was more effective than FI 203. In the trial using FI 161, soil samples after drill application at 8.5 × 1014conidia per ha showed infectivity against larvae ofI. rubricepsfor up to 4 mo in bioassays. Rates of infection and mortality were significantly related to concentrations of conidia in the corresponding samples. However, numbers of larvae in the field 1 and 2 yr after planting were not affected by treatment in either trial. Larval densities were not high, andM. anisopliaemay be more effective under other circumstances.