Crop models such as CROPGRO have been applied for simulation of growth and yield of several crops, including groundnut (Arachis hypogea L.). These models take into account the impact of some important climate elements such as temperature, radiation and rainfall on plant growth and development. If the effects of pests and diseases on plant growth and development could be incorporated in these models, they can serve as a valuable tool to study the impact of pests on crops. Here the population dynamics of a pest groundnut leafminer (Aproaerema modicella - Deventer) were modeled and linked with the peanut crop model of CROPGRO. Published data of the effects of temperature on growth rate, mortality, fertility and fecundity of groundnut leafminer were used and their combined effect on population dynamics was simulated. Using the published study of leaf area damage caused by the larvae of leafminer, daily leaf area damaged by the pest was modeled. This leaf area damage was incorporated in the CROPGRO model to simulate groundnut growth and yield in the presence of the pest leafminer. The linkage of the pest leafminer model with the peanut model-CROPGRO is generic so that it can easily be adopted for other pests. The results showed an optimum temperature of 26o C to 30o C for maximum leafminer population growth. Estimated pod yield reduction due to leafminer model varied between 9 to 54 % when moderate to high initial leafminer populations were assumed in the simulation. This linked model was verified for performance and found to give reasonable pest population variation and pod yield variation. The leafminer model can be further improved for population estimation under natural field conditions, such as influence of predators.