The New York Times covers this paper on how bean leaves help fight bedbug infestations. The leaves in question have tiny hooks that trap the bedbugs’ legs as they crawl over them. Using these leaves are a common folk remedy for getting rid of bedbugs in Eastern Europe. From the New York Times :

The first task was to determine exactly how the hooks — the technical name is trichomes — worked. The process was viewed through an electron microscope, Dr. Loudon said. “The foot comes down onto the surface, but as it’s lifting up, it’s catching on these hooks,” she said. “The point is pointing down. So all of their legs get impaled.”

“And as soon as one leg gets caught,” she added, “they are rapidly moving legs around and try to get away on the surface. That’s when they get multiply impaled.”

…

On the natural leaves, bugs were snagged, on average, after six steps, or locomotory cycles. (In one cycle, each of the insect’s six legs moves once.) Once stuck, they tried to free themselves, but they usually ended up just flailing in place around the impaled limb.