Codling moths may look harmless, but their larvae wreak havoc in orchards, burrowing into fruit and eating them from the inside out. Pesticides have always been the solution to the old “worm in the apple” problem, but pesticides kill all the insects in the field, even the good ones.

Instead of pesticides, farmers may soon use pheromones, those scented chemical messages animals release at mating time. Spreading synthetic, species-specific pheromones keeps male codling moths from finding females to mate with. No mating means no eggs, no larvae, and no more bad apples.

Scaling up agricultural pheromones has proved difficult, but innovative approaches to pheromone production (using yeast cells) and distribution (with the help of customized weather stations) are starting to make it happen.