An instance of aVespula vulgarisnest being usurped or adopted by aV. pensylvanicaqueen is reported. The gradual replacement ofV. vulgarisworkers byV. pensylvanicaworkers was evidenced by a gradual transition in the nest from tan, brittleV. vulgarispaper to gray, flexibleV. pensylvanicapaper. Intraspecific competition for nests by queens is probably common and interspecific competition for nests is likely where there is an overlap in the distribution of 2 closely related species.