Life cycles of 12 species of winter stoneflies from Quebec (Plecoptera; Capniidae and Taeniopterygidae)

The life cycles of 12 species of winter stoneflies belonging to the families Capniidae and Taeniopterygidae were studied in six river systems (seven sampling sites) in southern Quebec. Eight of the cycles were previously undescribed. All species were univoltine. Adults emerged as soon as the ice broke on the streams in late winter, except for Paracapnia angulata, Taenionema atlanticum, and Strophopteryx fasciata, which emerged about 3 weeks later. The simplest cycle occurred in Paracapnia opis, and P. angulata: egg development was direct and nymphal growth proceeded steadily from May to January. All other species showed evidence of a nymphal diapause interrupting development between June and September. In Allocapnia pygmaea, A. recta, C. vernalis, Taeniopteryx maura, T. parvula, and Oemopteryx glacialis, growth was completed by January, but A. minima, A. maria, Taenionema atlanticum, and Strophopteryx fasciata continued to develop through the winter and reached maturity just before emergence. Allocapnia recta, the first species to emerge, was also the first to mature, but the population showed much variability and the last nymphs to emerge were probably the only ones to survive and reproduce under Quebec climatic conditions.