The natural diets of many terrestrial predators such as spiders have yet to be investigated. In this study, I analyzed the diet of a web-building spider, Latrodectus hesperus Chamberlin & Ivie (1935), over one year in a natural habitat of coastal British Columbia, Canada. This is the first study to document the natural diet of L. hesperus over several months. I identified and measured 1599 prey items collected from L. hesperus webs and web sites between January and December. Spiders fed on ground-active prey from eight different orders of arthropods. Coleoptera and Hymenoptera were the predominant prey of L. hesperus in this habitat, combinely accounting for > 85% of the total prey catches and biomass. The other prey orders included, in order of abundance, Isopoda, Araneae, Dermaptera, Orthoptera, Lepidoptera and Diptera. Spiders captured prey mostly between May and October, when females oviposit, juveniles grow, and prey are most active. These results show that L. hesperus is a polyphagous predator that feeds primarily on prey from two orders of insects.