The sublethal effects of the entomopathogenic fungi, Beauveria bassiana (Balsamo) Vuillemin (strain GHA) and Metarhizium brunneum Petch (strain F-52), on larval weight gain, adult longevity, oviposition, pupation, and eclosion success were investigated in the southern masked chafer, Cyclocephala lurida Bland. Neither M. brunneum nor B. bassiana had a significant effect in reducing larval weight gains in body mass or interfering with the developmental growth of C. lurida. The fungi did not significantly decrease the adult longevity of either male or female chafers. Oviposition in this insect was strongly correlated with the time duration of male companion and female longevity, but neither fungal species had a significant impact. Pupation rate for the treatment with M. brunneum was significantly lower than that with B. bassiana, but neither treatment showed a significant difference from the control. Also, adult eclosion in this insect was not significantly affected by either M. brunneum or B. bassiana. Overall, no significant sublethal effect was detected in M. brunneum or B. bassiana by interference with the larval growth, adult longevity, oviposition, pupation, or eclosion success in C. lurida. This indicates little or no potential for the fungi in providing sublethal suppression of the pest population other than causing direct mortality of the insect.