The next time you spot a termite chomping down on wood, know that they’re not doing that job alone.

In this episode, Ed Yong explores the secrets behind termites’ power to digest an abundant source of food: wood. The key is microbes in their gut, but how do they get them? Ed checks in with Xinning Zhang at Princeton to find out that termites evolved from cockroaches into wood-eating specialists about 150 million years ago. The critical step was the evolution of a social behavior that passes microbes from termite to termite. Surprisingly, the termite way of being social is through… ahem… butt-licking. Or, more formally, “proctodeal trophallaxis.” Ed and Xinning examine footage of the microbes (protists) living inside the termite’s gut to see what their feast looks like up close.