Among populations of the same species, the diet composition varies depending on the environment, given the variation in diversity and abundance of available prey. Since Thoropa miliaris is a habitat specialist in reproduction, we tested the hypothesis that this specialization is also verified in its diet. We carried out the work in 10 localities in Serra do Mar and Serra da Mantiqueira, south‐eastern Brazil, where we collected frogs and evaluated prey availability. The environment did not provide significant variation in the diet of T. miliaris, and Formicidae was the prey category selectively consumed in greater volume, frequency and abundance in both mountain ranges. Therefore, we can state that T. miliaris has a selective diet on ants.