"In ants and bees, there are no sex chromosomes. Instead, sex is determined by whether or not an egg was fertilized. If the egg isn’t fertilized, the offspring is male. If the egg is fertilized, it’s female. So male ants have no fathers, and they have half as many chromosomes as females. Poor little things."
Beatrice the Biologist: Clarification, Sex Determination, and Cheesecake