Mammal blood is an unusual meal. It’s loaded with proteins and fats, but bereft of some vital nutrients like B vitamins. If you’re going to make a living off vampirism, you need to somehow supplement your diet. Bedbugs do it with bacteria. Scientists have suspected as much since the 1920s when they discovered that bedbugs have a pair of organs called bacteriomes that are full of bacteria. But it wasn’t till 2010 that Takema Fukatsu from the National Institute of Advanced Industrial Science and Technology in Japan finally identified the species that lives in these organs.

It’s called Wolbachia. Fukatsu found it in the bacteriomes of every bedbug he examined, and showed that females pass it to their offspring when