We studied the diet of Elachistocleis bicolor captured in pine, eucalypt, and unmodified environments in Uruguay. Comparisons between seasons (active, inactive) and among three environments (pine, eucalypt, unmodified), were made using rarefaction analyses, importance indices, and non-parametric tests. Elachistocleis bicolor has a specialized diet composed mainly of Pheidole and Solenopsis ants and termites. The diet of E. bicolor includes a high number of prey per individual, suggesting active search as a foraging strategy. The consumption of myrmicine ants (i.e., Solenopsis) represents a source for potential toxic skin secretions that in E. bicolor may be used to avoid being attacked in the ant nests used for shelter during aestivation, as occurs in the microhylid Phrynomantis microps. Diets in forested environments were richer in both periods, which may reflect the colonization of opportunistic ant species in these environments. Ants were more important in the eucalyptus plantations, particularly in the inactive period, whereas termites were more important in the pine plantations mainly in the inactive period. These environmental and seasonal differences in diet are consistent with the temperature and humidity tolerances of ants and termites, which are the main prey of E. bicolor.