The Economist July 15, 2013 COFFEE has many devoted drinkers. Its appealling aroma and caffeinated kick mean that 83% of all American adults drink it, 63% of them on a daily basis, according to a survey from the National Coffee Association. Yet despite the strong demand for coffee, some suppliers are unhappy. In Brazil, which produces a third of the world's coffee beans, farmers are striking over falling prices and burning sacks of coffee in protest. Why are coffee-growers feeling the strain? There are two main varieties of coffee bean: arabica and robusta. The former, which accounts for around 60% of the world's crop, is considered superior and fetches higher prices; the latter is a hardier crop, resistant to leaf rust, but has a more bitter taste. Most of the beans produced in Brazil are of the arabica variety. But these beans now fetch around $106 a 60kg bag, less than half of what farmers could get for them a couple of years ago. Farmers in Colombia and Eth...