There is now a considerable literature on chemical ecology, which had its beginnings in the study of insect pheromones. This beginning was possible only by combining the disciplines and techniques of biology and chemistry. For a biologist, it is difficult to understand the time frames of analytical and synthetic chemistry. A compound may take days to characterize and be available in minutes from a bottle on the shelf, or it may take years to characterize and synthesize. Chemists have a similar frustration: after an intense programme of work, the insect in question may not emerge for many...