Established pests are often overlooked as candidates for eradication or containment programmes because the use of traditional control techniques over very large areas usually becomes uneconomic. In such cases, classical biological control can be an attractive option. If biocontrol agents become established in equilibrium with the invasive species, there are no ongoing costs of control. Arriving at the point of biocontrol release, however, requires significant time and investment in research and testing, and success of biocontrol agents is not guaranteed. It is therefore advisable to undertake preliminary analysis of the likelihood of success. Simulation modelling using population dynamics models can be very useful in this regard. Here we develop a model for biocontrol of an invasive social insect, the European wasp (Vespula germanica) and derive the conditions for success of a biocontrol program.