This study was conducted to determine the effect of the fungus Zoophthora phytonomi (Arthur) on rates of parasitism by Bathyplectes anurus (Thomson) and B. curculionis (Thomson). These Bathyplectes species parasitized an average of 38.6 plus or minus 1.96 and 14.0 plus or minus 2.21% of the alfalfa weevils, Hypera postica (Gyllenhal), dissected during 1989 and 1990, respectively. However, B. curculionis parasitized only 0.15% of the 3,200 alfalfa weevil larvae reared during this study. Peak host density coincided with peak rates of parasitism by B. anurus for reared larvae and occurred [ 3 d before the peak rate of parasitism for dissected larvae. Peak incidence of parasitism for both reared and dissected larvae occurred [ 6 d before the peak in the epizootic of Z. phytonomi, Z. phytonomi indirectly caused high mortality of B. anurus after peak rates of parasitism and peak host density during 1989. B. anurus and the fungal pathogen have coexisted for 10 yr in central Kentucky with no apparent long-term reduction of B. anurus.