The Seasonal Abundance of Female Biting-Midges, Culicoides-Brevitarsis Kieffer (Diptera, Ceratopogonidae), in Coastal South-Eastern Australia

Abstract

Daily light-trap collections of female C. brevitarsis were made at three localities along the northern coastal plains of New South Wales. Numbers increased during spring, were maximal in summer, declined during autumn and were minimal in winter. The generation time was about 3-4 weeks in the summer and several cohorts of nulliparous midges, probably representing different generations, were detected from spring to autumn. Some breeding continued throughout the winter. Summer abundance appeared to be associated with high rates of reproduction in late spring or early summer, and this occurred when rainfall was adequate for good pasture growth. Midge survival was better in the summer than in other seasons of the year, and numbers of parous females increased rapidly whenever it rained, probably due to their increased survival and longevity. At each locality, numbers fluctuated throughout spring, summer and autumn, with peaks and troughs of abundance which were often not obviously associated with concurrent climatic conditions or cattle movements.