Sex by Surrogate

A male flour beetle (Tribolium castaneum) can mate and impregnate a female he has never met. No other animal is known to have sex by proxy in this way. Many males often mate with each female. The first male will deposit sperm in the female, then a second will arrive and use its spiny genitalia to scrape out his competitor's sperm, before mating itself. Much of the sperm of the first male is carried unwittingly by the second male on its genitalia. One in eight females are fertilised by proxy.