The effect on spores of Metarhizium anisopliae and Beauveria bassiana of insecticides recommended for the control of the brown planthopper [Nilaparvata lugens] and of insecticides that cause resurgences of this pest on rice was studied in the Philippines. The insecticides were mixed into the culture medium before planting or were surface-applied to hardened media. All insecticides significantly reduced spore germination of both fungi, M. anisopliae being the more sensitive. The recommended insecticides (monocrotophos, BPMC [fenobucarb], carbosulfan, and a mixture containing azinphos-ethyl and fenobucarb) reduced germination more than did the resurgence-causing insecticides (azinphos-ethyl, deltamethrin, parathion-methyl and MIPC [isoprocarb]), probably because a higher dose of the recommended insecticide was applied.