The life history of Pteronarcys dorsata (Say) (Plecoptera: Pteronarcyidae) in southwestern Virginia

Abstract

The life history of the giant stonefly Pteronarcys dorsata was investigated in a warm water fourth order river in southwestern Virginia. The life cycle of P. dorsata was univoltine with emergence occurring mid-March to 1st week of April. Adults lived up to 42 days in the laboratory. Mean fecundity was 242 eggs with up to four separate egg batches produced. Eggs hatched in 23 to 38 days. Early nymphal instars were collected in the river in mid-June. Nymphs reached maximum size by late November or December. During the warm months nymphs were found in mats of Podostemum ceratophyllum (river weed) and through the winter months under large unembedded rocks or leaf packs. The diet consisted of diatoms and detritus. Higher water temperatures of longer duration in the Little River probably allowed this species to complete its life cycle in 1 year rather than the 2 to 4 years previously reported.