NOVA

(person whistling) (bugs clicking) (soft lullaby music) For many of us, bed bugs basically define the word gross. After all, what could be more repulsive than an animal that sucks your blood while you sleep? Well, let me tell you a story that's sure to exceed even your worst nightmares. It's the story of bed bug sex. You see, male bed bugs have saber-like penises. When a male is ready to mate, he mounts any other bed bug that has just fed and is bloated with blood. If he finds a female, he takes his penis and stabs her in the abdomen, releasing sperm directly into her circulatory system. In fact, on rare occasions, he might even stab and inseminate another male if he's accidentally mounted one. He wounds the female but she does have an immune organ called the spermalege, which protects her from infection. For the record, females actually have fully functional reproductive tracts, but they use them exclusively for egg laying. So, just think, while you're sleeping tight, dozens of bed bugs could not only be sucking your blood, they could also be doing this. (upbeat electronic music) And do the Harlem Shake (intense electronic music) (sings in foreign language) Good night, bed bugs. (calm lullaby music) (laughs) Ew. (calm lullaby music)