The sequence of events in outbreaks of Austrosimulium pestilens Mackerras & Mackerras (Diptera: Simuliidae)

Abstract

AbstractStudies in Queensland showed that an outbreak of Austrosimulium pestilens Mack. & Mack. occurs if the water-level in a river rises enough to release eggs buried in the river-bed. Following such a rise, the larval development of A. pestilens was completed in 6–7 days in summer and 9–10 days in winter, and after a pupal period of 1·5–2 days in summer and 3 days in winter, adult eclosion began. Most flies emerging during the first 1–2 days were males, but females were slightly predominant later. A. pestilens emerged throughout the diel; at night there was a drop in the numbers emerging, and this was followed by a distinct early morning peak. Following a rapid rise and fall in river-levels, adult eclosion and mating occurred over a period of several days early in an outbreak, but after high river-levels of long duration, eclosion and mating occurred over a much longer period.