Insects do billions of dollars’ worth of damage to agricultural products annually, and they can also be the vectors of numerous diseases. A team of researchers led by Yeon Ho Je and Sang Woon Shin of Seoul National University, in South Korea, and Alexander S. Raikhel of the University of California, Riverside, have found five new insecticide candidates by examining the terpenes produced defensively by two plants: Lindera erythrocarpa, a common Asian shrub, and Solidago serotina, a pervasive North American perennial (Proc. Natl. Acad. Sci. USA 2015, DOI: 10.1073/pnas.1424386112). Researchers developing insecticides avoid compounds that might hurt the environment or human health by focusing instead on disrupting insect-specific proteins. This team focused on the juvenile hormone (JH) receptor in mosquitoes. Agonists acting on this receptor already form the basis of several insecticides, but antagonists, which could prove more effective, have not yet been found. The team showed that two of the terpenes, including LE3B, are JH antagonists and can retard the maturation of mosquito larva ovaries.