Three entomogenous fungi,Beauveria bassiana(Balsamo) Vuillemin,Aspergillus flavusLink, andFusarium solani(Martius) Appel&Wollenweber, were tested against healthy adults ofDendroctonus frontalisZimmerman at temperatures ranging from 5 to 30°C and relative humidities of 55, 75, or 94%. The greatest difference between the times for the beetles inoculated with the various fungi to achieve 50 or 90% mortality occurred in the range from 15 to 20°C. Variations in humidity did not significantly affect mortality. At the humidity levels tested, all inoculated beetles died sooner at 30°C than at the other temperatures. Mortality of mycotic beetles averaged 50% in 6.3 days and 90% in 11.0 days and was significantly different from that of the controls except at 5 and lO°C.