The leafhopper assassin bug, Zelus renardii Kolenati, is a natural enemy and stands out among species in the large New World genus Zelus Fabricius (∼60 spp.) by its introduction to and establishment in 3 biogeographic regions. We here present documentation of the distribution and habitat of Z. renardii in its native range in North and Central America and compare it with Z. tetracanthus Stål, a wide-ranging New World congener that apparently has not dispersed outside of its native range. In addition, we document and compare predatory and reproductive behaviors in the 2 species. Zelus renardii is widely distributed in the Western USA and shows a continuous geographic range south to Guatemala; Z. tetracanthus is broadly distributed across North and Central America and also occurs in Brazil. In Riverside County, California, Z. renardii is common in suburban and disturbed habitats in addition to certain natural areas, whereas Z. tetracanthus is usually restricted to natural areas. The behavioral comparison under laboratory conditions indicated that Z. renardii caught prey faster and that feeding duration in this species was shorter than in Z. tetracanthus. The duration of pre-copulatory behaviors in Z. renardii was shorter than in Z. tetracanthus, resulting in a shorter overall mating duration. Based on the higher percentage of egg batches that produced first instars in Z. renardii, this species may establish large populations under adverse conditions faster than Z. tetracanthus. Our observations on distribution and biology contribute toward an understanding of the differences in invasiveness between the 2 species.