Locust swarms have recently devastated large agricultural areas in Eastern Africa and Southern Asia. A team around Xianhui WANG and Le KANG at CAS Institute of Zoology and CAS University of Science and Technology has investigated 35 odorous compounds emitted by locusts and their interaction with over 100 locust receptors, with the result that 4VA triggers a receptor coded by gene OR35. Once 4 – 5 animals have aggregated, production of 4VA is increased and both gregarious and solitary locusts are strongly attracted to form a swarm, regardless of age and sex. Possible control measures now include laying pheromone traps to lure locusts, or using gene-editing technologies to prevent locusts from sensing 4VA, thus preventing swarms.