Bivoltine Entwicklungszyklen bei Sympetrum striolatum (Charpentier) in Mitteleuropa (Anisoptera: Libellulidae)

After an unusual long and hot summer in 1991 and 1992, a second emergence peak was observed in October, suggesting the possibility of an occasional bivoltinism. This hypothesis is supported by further, hitherto partly unpublished evidence. It is demonstrated that a single summer might suffice for completion of embryonic and larval development. Autumnal phenology and hibernation are discussed in relation to a second annual generation.