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Insect societies are vulnerable to exploitation by workers who reproduce selfishly rather than help to rear the queen's offspring. In most species, however, only a small proportion of the workers reproduce. Here, we develop an evolutionarily stable strategy (ESS) model to investigate factors that could explain these observed low levels of reproductive exploitation. Two key factors are identified: relatedness and policing. Relatedness affects the ESS proportion of reproductive workers because laying workers generally work less, leading to greater inclusive fitness costs when within‐colony relatedness is higher. The second key factor is policing. In many species, worker‐laid eggs are selectively removed or ‘policed’ by other workers or the queen. We show that policing not only prevents the rearing of worker‐laid eggs but can also make it unprofitable for workers to lay eggs in the first place. This can explain why …