Migrating moths (Lepidoptera) collected in tower-mounted light traps in northern New South Wales, Australia: species composition and seasonal abundance

Abstract

AbstractLight traps were operated between September and April for five years on towers on mountain tops at two locations in northern New South Wales, Australia. The traps were designed so that their lights could only be seen from above, and therefore only insects engaged in high altitude flight, presumed to be migrants, were captured. The catch consisted mostly of Noctuidae and Sphingidae. Sweep netting failed to reveal local breeding, and for many species there were few host plants close to the traps. A total of 51,580 moths were trapped at Point Lookout and 10,223 at Mt Dowe. Sphingids, mostly Hippotion scrofa (Boisduval), comprised 26.9% of the catch at Point Lookout, but only 2.6% at Mt Dowe, and there were more species of noctuids at Point Lookout (44) than at Mt Dowe (15). The most common noctuid species were Agrotis infusa (Boisduval), Mythimna convecta (Walker), Helicoverpa punctigera (Wallengren), H. armigera (Hübner), Dasygaster nephelistis Hampson and A. munda Walker. Known or suspected migrants comprised 94.6% of the catch at Point Lookout and 99.9% at Mt Dowe. However, there were at least 24 species not previously suspected as migrants. The seasonal distribution of catches varied between sites and years. Some species showed peaks in both spring and autumn in some years, but only in spring in other years. Many of the less common species were caught only in summer and autumn. Large catches were usually obtained overs short periods (1–2 nights), separated by long periods when catches were very low. These large catches, which were thought to represent major migrations, accounted for 76% of the catch in 3% of the trapping period at Point Lookout, and 87% of the catch in 2% of the trapping period at Mt Dowe.