Effects of emergence characteristics on longevity and maturation in the dragonflySympetrum danae (Anisoptera : Libellulidae)

Size, sex-ratio and mean abdomen length of an emergingSympetrum danae population showed significant yearly variations. It is argued that weather plays a major role. A consistent female-excess at emergence existed.Longevity estimates in the field were highly biased by emigration, especially at an early age, and seemingly more so in females than males. The larger, early emerging individuals emigrated more readily immediately after emergence and lived longer if they stayed in the area, than the smaller, late-emerging ones. This relation was especially clear in males.The shorter maturation in males found in the field was attributed to a sex-specific bias in the field. Maturation-time was found to be inversely related with emergence-data. No effects of abdomen length, weather or density could be demonstrated.