The reason bees testicles explode after sex and their genitals fall off has to do with preserving their genetic code, and ensuring it is their genes that go on to populate the new colony. You’re wondering how bees testicles exploding and genitals falling off after sex can ensure only their semen is the one that goes on to impregnate the queen bee. It really is quite simple. When the bees testicles explode and their genitals fall off they do so while in the vagina of the queen bee. This effectively plugs the vagina and prevents the queen bee from copulating with any other male drone bees and allowing her to be fertilized any further. If bees were the same as dogs for instance, the queen would be able to fornicate with several male drones and the offspring would have multiple fathers.