Oncopeltus fasciatus, known as the large milkweed bug, is a medium-sized hemipteran (true bug) of the family Lygaeidae. It is distributed throughout North America. It ranges from Central America through Mexico and the Caribbean to southern areas in Canada. Costa Rica represents this insects southern limit. It inhabits disturbed areas, roadsides and open pastures. Due to this widespread geographic distribution this insect exhibits varying life history trade-offs depending on the population location.