When looking for mates, some ant species don’t venture far from the family tree. In colonies of an ant from the Philippines, pictured above (Cardiocondyla argyrotricha), newly mature males will fight to the death to mate with their sister-queens. But often, there aren’t enough males to go around. So to form new colonies, virgin queens mate with their own sons, researchers report in Naturwissenschaften. To make the discovery, the scientists set up 31 artificial ant colonies with an unhatched queen and a set of sterile female worker ants and watched for the emergence of unfertilized male and fertilized female pupae. In all the colonies, queens could not lay female eggs until after a son was ready to reproduce. They even filmed one mother-son pair in the act of mating. Such coupling in ants, wasps, and bees is rare because it usually produces large numbers of sterile males. But these Oedipal insects seem to have found ways to avoid that problem.

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