THE coffee-berry borer is a pesky beetle. It is thought to destroy $500m-worth of unpicked coffee beans a year, thus diminishing the incomes of some 20m farmers. The borer spends most of its life as a larva, buried inside a coffee berry, feeding on the beans within. To do so, it has to defy the toxic effects of caffeine. This is a substance which, though pleasing to people, is fatal to insects—except, for reasons hitherto unknown, to the coffee-berry borer. But those reasons are unknown no longer. Read the rest at The Economist.