A simulation model of a major mite pest of stored grain,Acarus siroL., was developed to predict the maximum rate of its population growth and survival by interpolating daily rates of growth of its population derived from published studies. The model simulates the population dynamics at −10 to 40°C and 20–90% RH without resource limitation or natural enemies. The model's predictions were in reasonable agreement with naturally occurring mite populations in bulk stored wheat in granaries in Manitoba, England, and Czechoslovakia.