The clam shrimp Eulimnadia texana exhibits a rare mixed mating system known as androdioecy. In this ephemeral pond branchiopod crustacean, males coexist with hermaphrodites, which can outcross with males or can self-fertilize. Here we provide an estimate of the relative longevity of males to hermaphrodites (1 - s), an important parameter of a model that was developed to explain the conditions under which this system would be stable. Under both optimal rearing conditions and variable social conditions, hermaphrodites from two study populations lived significantly longer than did males. Since various aspects of mating have been found to be costly to males and females/hermaphrodites in other taxa we explored this possibility as well. Hermaphrodites showed no differences in longevity when kept in groups with different mating opportunities. Males, however, lived significantly longer under conditions of increased mating opportunities, a result contrary to what we had expected. Behavioral observations, however, suggested that male-male interactions may have been deleterious to males living in groups with little opportunity to mate. This was confirmed by an additional study where individual males were kept with or without hermaphrodites. Nevertheless, under these conditions we still did not detect any longevity cost of mating for males.