To minimize damage and reduce the need for insecticide sprays, crops have been genetically engineered to produce bacterial proteins that kill key pests but are not harmful to people or wildlife. However, widespread planting of such transgenic crops has led to rapid adaptation by some pests. A new study in the Proceedings of the National Academy of Sciences reveals a novel genetic basis of resistance to transgenic crops in one of the most important crop pests in the U.S. – the corn earworm.