Impact of warm weather events on prolongation of the life cycle of Stomaphis Walker (Hemiptera, Aphididae, Lachninae)

Termination of the life cycle of sexually reproducing aphids usually takes place in autumn, during October and November, in the climatic conditions of Central Europe. However, episodes of warm weather are suspected to trigger prolongation of the life cycle. Observations of Stomaphis spp. in early winter of 2013/2014 in southern Poland support this thesis. Surprisingly, adult females of two species were collected as late as early January and early March. High daily temperatures during this period were the probable cause of aphid survival, despite frosty nights. The possibility of the influence of warm weather episodes (higher temperature) on prolongation of the life cycle in aphids, or such episodes causing permanent parthenogenesis, is discussed.