Hypericum perforatum L., St. John's - wort (Hypericaceae), is a cosmopolitan weed that, when eaten by livestock, causes photodermatitis, reduced weight gain, and, in extreme cases, death (Giese 1980). Chrysolina hyperici (Forester) and Chrysolina quadrigemina (Suffr.) (Coleoptera: Chrysomelidae) dramatically reduced populations of H. perforatum when introduced into Australia (Clark 1953) and the United States (Holloway and Huffaker 1951; Holloway 1957). These species also have served as effective biocontrol agents when introduced into central British Columbia (Smith 1958), Ontario, and Nova Scotia (Harris and Maw 1984). This paper surveys the distribution of Chrysolina spp. in eastern Ontario, 18 years after initial release of both species.