The fruit tree mealybugRastrococcus invadensWilliams, accidentally introduced into the West African region in the early 1980s, has been the subject of a successful biological control programme in Togo and elsewhere in West Africa. It is now kept at low population densities by the introduced specific parasitoidGyranusoidea tebygiNoyes. The sociological and economic impact of this successful biological control programme is evaluated. The economic assessment strongly suggests that the programme was very cost‐effective. In addition, substantial non‐quantifiable social and cultural benefits can be recorded.