Why are females polyandrous? This question is highly prominent in the eusocial Hymenoptera, because monogamy is essential for sociality. Extreme polyandry is particularly interesting, because it can hardly be explained classically by involving fitness returns of intracolonial genotypic variance (IGV), which diminish with increasing mating frequencies. However, extreme polyandry regularly occurs, e.g., in the highly advanced army ants. This dissertation investigates the relevance of IGV hypotheses in this important model system. IGV is confirmed as driving force. This is shown by an increasingly equalized paternity distribution by queens with higher paternity frequencies, against monopolization interests of males, indicating over proportional, non-linear fitness gains from intracolonial diversity, as well as queen control over resulting sexual conflicts. Consequences are a male biased sex ratio and gene flow pattern. Evolution and consequences of extreme polyandry are closely connected with each other and with the highly specific life history of the army ants.