Details of the life history, the effects of relative humidity and temperature on survival and reproduction, and the predatory ability of Aleurodothrips fasciapennis Franklin were examined under laboratory conditions. Stage-specific development and adult longevity were similar between sexes, and the adult sex ratio was 1:1. Females laid 23.3 ± 18.0 eggs of which 83% hatched. The survival rate of first instars to adulthood was 82%. The intrinsic rate of natural increase (rm) was 0.04, assuming a zero or 5.4 day pre-oviposition interval. Temperature did not affect the proportion of eggs that hatched, the proportion of first instars surviving to adulthood or adult sex ratios. However, female fecundity was dependent on temperature being highest at 24 ndash 28°C. Relative humidity did not affect adult sex ratio or female fecundity but the proportion of eggs hatched and the survival of first instars to adulthood increased as relative humidity increased. Few eggs hatched when relative humidity was <65%. Larval and adult female A. fasciapennis were voracious feeders but the number of prey killed per progeny was high, suggesting A. fasciapennis was inefficient at converting prey into progeny biomass. The potential value of A. fasciapennis as a biocontrol agent of Aonidiella aurantii (Maskell) on Australian citrus is discussed in terms of its rm, prey killing power and environmental adaptability. It is concluded that population growth of A. fasciapennis should exceed that of A. aurantii under field conditions but A. fasciapennis may be of little value against A. aurantii on citrus grown under conditions of high temperature and low humidity, or when prey densities are low.