Revision of the life history of the High Arctic moth Gynaephora groenlandica (Wocke) (Lepidoptera: Lymantriidae)

Abstract

Many studies have explored the adaptations of arctic and alpine Gynaephora species (Lepidoptera: Lymantriidae) to their environment, and base-line life-history information is important for the interpretation of such studies. Data and observations on G. groenlandica (Wocke) collected in recent years at Alexandra Fiord, Ellesmere Island, Canada, contradict some of the life-history information previously published for this species from the same site. Detailed analysis of larval head capsule widths and consideration of growth ratios indicate that there are seven rather than six larval instars and that the pattern of development does not deviate significantly from that defined by the Brooks-Dyar rule. Field-rearing of larvae indicates that first-instar larvae overwinter, while field- and laboratory-rearing both indicate that larvae moult once per year, every year. These data and observations greatly shorten and simplify the life history from that previously published and suggest a life cycle of 7 rather than 14 years. This revised life cycle is not presented as an absolute, in recognition of the potential for individual variation, but rather as typical of the developmental pattern of most of the population. As such, it should provide a useful base line for further studies, especially those addressing the influence of predicted climate change in the Arctic.