Worker policing in the common wasp Vespula vulgaris is not aimed at improving colony hygiene

In insect societies, eggs laid by workers are frequently killed by other workers-a behaviour known as worker policing. The traditional explanation of worker policing is that it is a mechanism to resolve intra-colony conflict, and maintain the reproductive monopoly of the queen. Recently, Pirk et al. (2004) proposed that worker policing instead is aimed at removing unviable worker-laid eggs and is ultimately just another example of hygienic behaviour. Here we test this hypothesis for the common wasp Vespula vulgaris, a species with highly effective worker policing. We show that worker-laid eggs from queenless colonies have a lower hatch rate (68%) than queen-laid eggs (82%). Analysis of egg laying rates of queens and workers, however, shows that the difference is not big enough to explain the apparent absence of adult worker-derived males in this species.