from paper produced by chewing old and weathered, but dry wood. Worker-queen conflict It is common for a conflict to exist between individuals in social groups as they often have different goals, which spurs conflict. Through evolution, mechanisms to encourage group effectiveness and minimise individual's selfish interests have evolved. Social policing is an important example in which "mutual enforcement limits the success of selfish individuals." Differences in objectives for queens and workers bees can be attributed to differences in relatedness between them. Worker policing is a consequence of this difference. Differences in relatedness Although workers are generally unable to mate, they have functional ovaries that allow them to lay eggs. Because these eggs are not fertilised, they would become male wasps. Workers would want to produce such wasps as they would be more closely related to their own sons than to their mothers' sons, or brothers. However, it is not in the queens best interest for workers to produce offspring. This is because a queen would be more closely related to her own offspring (r=1/2) than to her offspring's sons (r=1/4). When the queen mates with many males, workers are more closely related to their brothers (queens' sons) since r=0.25, than to the sons of other workers since r<0.25 for half-nephews and nephews). The differences in relatedness of offspring between workers and queens represents a conflict of interest between workers and queens, as both workers and queens want to maximise the survival of the offspring more closely related to themselves, according to the selfish gene perspective. Worker Policing With regard to conflict over who bears males, policing refers to the process in which individual workers are precluded from reproducing. Policing can be carried out by the queen or by workers. Two different approaches can be taken to achieve policing: worker-laid eggs can be eliminated or reproductive workers can be treated aggressively. According to kin selection theory, queens should carry out policing because queens are closer relatives to their own sons than to their workers' sons - that is their daughters' sons. When queens mate with multiple males, workers should police because workers are generally closer relatives of the queen's sons than to the workers' sons. Vespula rufa has much lower rates of worker policing than other species in its genus. Moreover, the queen polices a substantial percentage of worker-laid eggs in the species. Interactions with other species Parasites Parasites of Vespula rufa include the beetle Metoecus paradoxus (a larval parasitoid and the fly Conops flavipes (an endoparasite). The larvae of Volucella pellucens (a hoverfly) act as scavengers. Vespula austriaca is an obligate social parasite on V. rufa in Europe and Asia." Because of its parasitic behaviour, V. austriaca does not produce workers, but relies on the host workers for rearing. The queen of "V. austriaca" invades the V. rufa host colony, and drives away the V. rufa queen. Predators Badgers (Meles meles) destroy Vespula rufa nests, consuming the occupants, combs, and envelope. The wasps stings don't threaten badgers as thick skin and body hair protect them from stings. Great tits (Parus major) are also predators of V. rufa, digging their nests out of cavities. The larvae of Volucella pellucens (a hoverfly) act as scavengers. Leaving the nest There are many factors affecting whether worker wasps will leave the nest. Important considerations include temperature, light intensity, and the existence of other wasps. Relative humidity and atmospheric pressure do not affect V. rufa'''s decision of whether or not to leave the nest. Orientation flights occur so that V. rufa can familiarise themselves with the entrance to their nest and recognise it when