Nearctic “Slug” Sawfly Larvae of the Genus Caliroa Costa (Hymenoptera: Tenthredinidae): New Rearing Records and a Summary of Hosts, Descriptions, and Distribution Records

Abstract. Hosts, larval descriptions, biology, and distribution records are reviewed for the 16 described Nearctic species of Caliroa Costa (Tenthredinidae). We report the first rearing records for C. lunata MacGillivray, which feeds on Staphylea trifolia L. (Staphyleaceae). Caliroa obsoleta (Norton), previously known from Quercus L. spp. (Fagaceae), has now been reared from Populus tremuloides Michx. (Salicaceae). The larva of another Quercus feeder, C. petiolata Smith, is described and illustrated for the first time. A key is provided to both known and unidentified larvae, drawing from the literature and new observations, including an extensive review of online photographs.