In Australia, the introduced house mouse, Mus domesticus, causes obvious and severe agricultural damage, particularly during mouse plagues where population densities may exceed 1,000 mice/ha. The aim of any pest control is to reduce the damage caused by the pest, not to reduce pest numbers per se. Management of mice is generally reactive, and much damage has already occurred by the time control methods are applied. Most of the time, mice are in low numbers and cause little damage to crops. There is limited understanding of how mice damage plants or how crops recover or compensate for damage inflicted by mice. However, it is known that wheat crops can compensate for damage early in the growth of the crop, but not in later growth stages. We need to know the relationship between the density of mouse populations and loss of yield at key phases of crop growth so that management targets can be established. I modelled mouse population density and the feeding requirements of mice in a crop simulation model, and estimated yield loss. A sigmoidal curve best described the data and showed that the density of mice at which 5% loss occurred was 42 mice/ha. Management therefore is required early and over large areas to reduce reinvasion and to keep mouse densities less than 42 mice/ha at sowing