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The fungicides benomyl, chlorothalonil, thiabendazole, and fentin hydroxide were applied alone and in combination with methyl parathion or methomyl to soybeans. Larval population levels of Plathypena scabra (F.), Anticarsia gemmatalis (Hubner), and Pseudoplusia includens (Walker) were monitored as well as selected arthropod predators and the incidence of the fungal entomopathogens Nomuraea rileyi (Farlow) Samson and Entomophthora gammae (Weiser). Application of fungicides at the recommended rates failed to suppress an epizootic of E. gammae in P. includens populations. The incidence of N. rileyi was suppressed in a low density population of A. gemmatalis . When larval density increased, no difference was detected in the incidence of N. rileyi infection in treated and untreated plots. Differences in predator population levels were not observed in a 1976 P. includens test but generally lower predator populations were noted in the 1977 P. includens-A. gemmatalis test in fungicide and/or insecticide treated plots. Fentin hydroxide alone and treatments which included methyl parathion or methomyl reduced larval populations of P. scabra and A. gemmatalis . Only treatments containing methomyl reduced larval populations of P. includens. Pseudoplusia includens population resurgence was detected following treatments with benomyl and methyl parathion, chlorothalonil + methyl parathion and fentin hydroxide + methyl parathion. Anticarsia gemmatalis population resurgence followed treatment with fentin hydroxide + methomyl.