Across-species mating is a surprisingly widespread phenomenon. Reproductive interference occurs when across-species mating leads to fitness costs for one or both species involved. These costs can impact population persistence, habitat partitioning, species boundaries, and the distributions of traits used in mate choice within populations. Thus, it is important to understand the causes and consequences of across-species mating. In Florida, USA the squash bug, Anasa tristis, co-occurs with a recently introduced, smaller congener, A. andresii. Male A. andresii are commonly found copulating with the larger female A. tristis in the field. We found that male A. andresii prefer large females in general and may seek out females of A. tristis over females of their own species. We found surprisingly little evidence of fecundity costs of across-species mating and living in communities that contain members of both species. One reason for the low costs may be improved species recognition after a heterospecific mating; females that mated with a heterospecific avoided these males in the future.