mated more than once. As different colonies may have differences in the relatedness of workers, conflict over sex ratio arises. Fisher's theory of equal investment supports that a colony with a 50:50 sex ratio is the most beneficial due to both males and females having the same expected reproductive success. In colonies with an active foundress, workers may not produce male offspring of their own if it means a healthier colony. Additionally, a foundress may eat the eggs laid by workers to maintain balance if she was unable to prevent workers from laying eggs in the first place. The reverse is expected to occur as well. Indirect evidence also supports the occurrence matricide within colonies, and queen death is noted to be high in P. gallicus. Interaction with other species Predators Ants are a major threat to colonies prior to the emergence of the first workers. Members of the genera Tapinoma, Pheidole, and Tetramorium are known to be able to decimate a young nest. These ants feed on both larvae and pupae. Advanced predation may result in a foundress having to begin a new nest from scratch or otherwise usurp the nest of another foundress. If there are already workers at the time, the colony swarms to a nearby point to being a new nest or, if there are many workers, the colony may split up to form several smaller nests. However, only the fertile foundress will produce female offspring to complete the colony cycle, and secondary nests will only produce male offspring. If one of the secondary nests is lost, such as to predation, its workers will instead rejoin a sister colony instead of trying to start a colony from scratch for a third time. Parasites Strepsipterans belonging to the genus Xenos are known to infect and parasitize the genus Polistes, with Xenos vesparum especially documented in P. gallicus. Young members of the colony are particularly susceptible while within the brood cell, in contrast to adults that have departed their cell. These Xenos parasites are most visible in pupae and neotenic adults, though may affect all live stages. When parasites have higher prevalence, individual brood members of a nest also tend to be hosts to multiple Xenos parasites. They tend to infect these wasps either through phoretic transport. Here, the parasite's first instar larvae are able to attach to wasps’ abdomens at flowering patches or by infecting masses by