Seasonal patterns of activity in geometrid moths (Lepidoptera: Geometridae) from a lowland and highland eucalypt forest in Tasmania

Abstract

Activity patterns of geometrid moths were compared in two areas, one in wet eucalypt forest at high altitude and the other in mainly dry forest at low altitude in Tasmania. One hundred and twenty-six species were able to be grouped into six distinct groups (i.e. spring, spring and summer, summer, autumn, autumn and winter, all year) in terms of their patterns of seasonal occurrence. Three of the 16 species common to the two sites differed in their seasonality of occurrence, with their length of occurrence being extended at Old Chum Dam compared with Central Plateau. Moth numbers strongly reflected monthly changes in minimum temperature, with moth activity being greater at the high altitude site than at the low altitude site for an equivalent temperature. However, a given change in minimum temperature led to an equivalent change in the magnitude of moth numbers at both sites. These seasonal patterns of occurrence must be considered in the planning of biodiversity surveys.