A study from the University of Sao Paulo published in the Journal of Insect Behavior describes the shocking behavior of coffee berry borers. These insects, which Discovery News calls "the most serious pests of coffee plants worldwide," have sex in coffee beans before they're roasted into the delicious drink.
The coffee berry borers are a type of beetle native to Africa. The females are just .07 inches long, and the males are about .06 inches long — tiny enough to get down inside coffee beans.
That's not even the weirdest part — the beetles' coffee bean sex is also incestuous. Weliton Dias Silva, author of the study, writes that females "have to be copulated by their sibling males before leaving the native coffee fruit to improve their chances of successful colonization." And sometimes, females don't even need their brothers — they can reproduce on their own, through parthenogenesis.
So how can you tell if your coffee beans are the site of insect sex? Discovery News reports that the female beetles bore "minute holes" to escape from the beans, and the beans may also seem more hollow than others. If you're a fan of Coffee arabica, you might be more at risk — it's also the beetles' coffee of choice. You probably shouldn't be too concerned, though, because most of the "infested" beans are taken off the market.
Read more about the coffee berry borers — and view close-up photos of the insects, if that's your thing — over at Discovery News.