An old folk remedy involving hairy bean leaves strewn around the bedroom may have a new life as a modern bed bug trap, according to new research from the University of California, Irvine and the University of Kentucky. With insecticide resistance on the rise, such a device could be a helpful tool for treating bed bug infestations.
Although its mechanisms weren’t known at the time, the tactic dates back to at least 1678, when the English philosopher John Locke wrote of placing kidney bean leaves under the pillow or around the bed to keep bed bugs from biting as he traveled through Europe.
In the early twentieth century, the approach was also common throughout the Balkans, according to a 1927 report from the Imperial and Royal Austro-Hungarian Army. That report suggested the leaves stunned the bloodsucking bugs as they traveled from hiding places to their sleeping hosts during the night; in the morning, the bug-covered leaves were removed and burned (dense infestations could allegedly amass over two pounds of the buggy leaves in a single room).
American entomologists studying the effect in the 1940s noted the bed bugs “could hardly be induced to move from the leaves,” and microscopic images suggested that fine, curved hairs called trichomes on the bottom of the leaves snagged the bugs’ feet.