The life histories of many of the stoneflies (Plecoptera) of south-eastern mainland Australia

Abstract

Collections of stonefly nymphs and adults were made at monthly intervals in 11 streams in Victoria throughout a year, and these were supplemented by collections from other streams. By following seasonal changes in the size distribution of the nymphs, and the occurrence of adults and cast skins, and by determining the length of development of the eggs under simulated stream conditions, the life cycles of 27 species were worked out in detail, and some information was obtained on a further seven species. The 34 species include representatives of all the four families that occur in Australia, and for several species the cycle was worked out in two or more streams. It is concluded that the life cycles in Australian species are generally much less rigid than those found in the northern hemisphere, and that they provide evidence of great adaptability to an uncertain climate. Each species therefore tends to occupy a broader ecological niche than do northern hemisphere ones and this possibly accounts fcr the relatively small number of species that are found in south-eastern Australia.