The European oak borer, Agrilus sulcicollis Lacordaire, a newly detected alien species in Canada, is reported from southern Ontario. This species is illustrated and diagnosed to facilitate its recognition among other North American species of Agrilus Curtis. Data are provided on its phylogenetic affinities, host plants, native distribution, and all North American records known to date. The other eight non-native Agrilus species known in North America (A. cuprescens (Ménétriés), A. cyanescens Ratzeburg, A. derasofasciatus Lacordaire, A. hyperici (Creutzer), A. pilosovittatus Saunders, A. planipennis Fairmaire, A. sinuatus (Olivier), and A. subrobustus Saunders) are briefly discussed.