They cover cars, roads, even blocking hospital access. Over the past few weeks, millions of Mormon crickets (Anabrus simplex) have invaded the town of Elko, Nevada. They travel by the thousands, devouring all crops, with a preference for cereals such as wheat, barley and oats. Mormon locusts live between three and six months and eat the equivalent of their weight in vegetation every day. According to specialists, this phenomenon can be characterised by a systematic increase in heat waves. Photo: AP/Rick Bower