Slugs Somehow Can’t Tolerate a Stimulant

Caffeine, a common stimulant, can kill slugs and snails and can discourage slugs from munching on treated plants, suggesting a possible approach to environmentally friendly pest control for gardens and cropland, Hawaiian researchers reported in the June 27 issue of Nature. A team at the U.S. Department of Agriculture research center in Hilo found, for example, that when they let slugs bury themselves in potted soil and then applied a 2% caffeine solution to the dirt, 92% died within two days.

In another experiment, slugs tended to avoid eating cabbage leaves that had been treated with caffeine. The team also found that caffeine solutions killed mature orchid snails. It is not clear how the compound kills the pests, however.