Entomophthorales pathogenic to insects and mites often cause epizootics in their host populations, but some have been difficult to culture in vitro and, therefore, to develop as biopesticides. Grace's insect cell culture medium supplemented with lactalbumin hydrolysate and yeastolate has allowed growth of several species which until recently were referred to as obligate parasites. The research reported here was designed to evaluate the effects of the salts, vitamins and amino acids used to prepare the insect cell culture medium on in vitro growth of Batkoa sp. and Furia sp., pathogens of the spittlebug pests of pasture and sugar-cane in Brazil, and Neozygites floridana, a pathogen of several mite species. Also, several sources of carbon and nitrogen were examined. Batkoa sp., Furia sp. and N. floridana were similar concerning their growth patterns in a basic medium with added salts, vitamins and amino acids, as well as with a combination of all three compoments. The addition of salts to the basic medium of sugars plus lactalbumen hydrolysate and yeastolate caused a significant increase in biomass production of the three fungal species. The addition of vitamins and amino acids had less effect. Batkoa sp., Furia sp. and N. floridana are similar in growth patterns in media with various sources of carbon, but different in media with different sources of nitrogen. The production of the three fungal species is significantly higher in medium containing 2.66% glucose than in medium with 2.66% sucrose. The addition of 0.1% monossacarides to media containing 2.66% sucrose did not significantly increase biomass production.