The development and fecundity of the citrus rust mite,Phyllocoptruta oleivora(Ashmead) were studied under constant temperatures ranging from 14 to 31°C. The developmental threshold based on mean generation time was 11.07°C. The highest developmental rate occurred at 29°C. The intrinsic rate of increase, net reproduction, total egg production, and mean generation time were fitted to functions of temperature. The optimal temperature for mite population growth as measured by both r andR0was ≈25°C. The cumulative emergence and egg production wcre fitted to 2-variable logistic distribution functions of temperature and cohort age. The probability density function is also derived and truncated so that it will integrate to 1 over time between 0 and + ∞. In our case, ignoring the truncation results in an error on the order of 0.005. The established functions will be used to build a mite population model, but they should be generally useful to researchers who describe insect development and phenology.