Biological and distributional data are reviewed for the Nearctic species of Metallus Forbes (Hymenoptera: Tenthredinidae), and new data are presented for each. Larvae of all four mine leaves of rosaceous plants. The introduced Palearctic species M. lanceolatus (Thomson) feeds on Geum L. and is multivoltine. The three native species feed on Rubus L. and are univoltine or bivoltine. Metallus capitalis (Norton) is found on raspberries across southern Canada and the northern US and is bivoltine. Metallus rohweri MacGillivray occurs on blackberries and dewberries in eastern North America; it is univoltine in Massachusetts, but previous studies indicate that it is bivoltine in New York and farther south. Metallus ochreus Smith is now known from Virginia to New Hampshire and is strictly univoltine, with immature larvae overwintering in leaves of bristly dewberry (R. hispidus L.). Parasitoids reared from Metallus include species of Eulophidae, Braconidae, and Ichneumonidae.