The optimal temperature for population growth of Naiadacarus arboricola, an acarid mite restricted to water-filled treeholes, is approximately 25°C. At this temperature mortality is lowest, developmental rate fastest, and larviposition greatest - thus providing for the highest intrinsic rate of increase (rm) of a population. Temperatures of 30°C or higher inhibit molting, and a temperature of I5°C does not allow the development of most mites to proceed past the tritonymphal stage. N. arboricola feeds on decaying leaves that fall into the treehole from surrounding vegetation. Food source (species of tree) has a great influence on the immature mortality rate, developmental rate, adult survivorship, reproductive success and intrinsic rate of increase of a population. Thus by contributing the food source, the species of plants surrounding a treehole determine the abundance of N. arboricola within the treehole. N. arboricola has a rather low intrinsic rate of increase compared to other acarid mites. This probably evolved as an adaption to the seasonal influx of food into the treehole, as well as to the stable habitat in which they live.