Scientists have identified an automatic behavior in flies that helps them assess wind conditions -- its presence and direction -- before deploying a strategy to follow a scent to its source. The fact that they can do this is surprising -- can you tell if there's a gentle breeze if you stick your head out of a moving car? Flies aren't just reacting to an odor with a preprogrammed response: they are responding in context-appropriate manner. This knowledge potentially could be applied to train more sophisticated algorithms for scent-detecting drones to find the source of chemical leaks.