The effect coffee has on human health has been the focus of considerable debate, but it is generally accepted that drinking a few cups a day won't harm most people. However, for certain garden molluscs it seems the opposite is the case. In 27 June Nature, Robert Hollingsworth and colleagues at US Pacific Basin Agricultural Research Center, Hawaii, show that high concentrations of caffeine are lethal to slugs and snails (Nature 2002, 417:915-916).

Hollingsworth et al. tested the effect of caffeine solutions on Veronicella cubensis (Pfeiffer) slugs and mature orchid snails Zonitoides arboreus (Say). They observed that 48 to 96 hours after an exposure to a 2% caffeine solution all slugs and snails had died. In addition, in a greenhouse test, a 2% solution of caffeine proved to be more effective in reducing the presence of snails than a solution of 0.195% metaldehyde, the commercial...

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