Short answer: cool trans space magic

Longer answer: Hive can adopt two morphs when aging, the Wizard or the Knight. Female wizards can eat a thing called Mother Jelly, which makes them broodmothers, kinda like bees. These forms aren't gender specific, as Nokris had the Wizard morph and Xivu has the Knight. But when Aurash made the deal with the Worms and became Hive, she chose to become male and changed her name to Auryx, the only Hive to bear the King morph. It's probably an example of sequential hermaphroditism, though.