Two species of crayfish were tested in the laboratory to evaluate the hypothesis that successful invaders use a broader range of chemical information than do displaced native species. The invasive species Orconectes rusticus reduced responses to food odors just as strongly when heterspecific (O. propinquus, O. virilis) alarm odors were introduced with food odors as they did when conspecific alarm odors were introduced at the same time as food odors. Individuals of the displaced native species, O. propinquus, did not reduce feeding responses as strongly when O. virilis alarm odor was introduced as with conspecific alarm odor or O. rusticus alarm odor. These results are consistent with the hypothesis that successful invaders use a wider range of information about their environment than do displaced native species.