Grain weevils alone cost the global economy about $35 billion, or a third of the world’s grain crop, every year. Various other beetle species damage dozens of crops including bamboo, palm trees, bananas, grasses, sugarcane, pines, and irises. “My research is about the evolution of interactions of various sorts,” Professor Brian D. Farrell says, “including those with plants, those with fungi that help insects attack plants, and those with bacteria that help insects digest plants.” His main focus of late has been on bark beetles, which cause about $7 billion of timber damage in the United States alone. “We spend tens of millions of dollars every year studying all aspects of their biology,” he says. “Why not spend another half million to understand their evolutionary relationships?” Studying beetles’ evolutionary biology, for instance, gave Farrell insight to a question that had puzzled scientists for decades – possibly centuries: Why are there so many beetles? In a paper published in the July 1998 issue of Science, Farrell concluded that it’s because “every time they colonized plants, particularly flowering plants, their diversity leapt up by several orders of magnitude” as the plants developed defenses to combat them.