A pedigree diagram. In the pedigree diagram, the expanded rectangular box shows a dummy sire which consists of 10 drone-producing sister queens represented by smaller circles. Each drone-producing sister queen contributes two drones which are represented by the smaller square boxes. All drone-producing sister queens comprising a dummy sire have a common dam queen and dummy sire, thus are related as sisters. The pedigree shows that mating takes place between overlapping generations.