MDI investigators previously discovered that the efficacy of crystalline contact insecticides depends on the crystalline form (a.k.a. polymorphs). Polymorphism in contact insecticides, however, and its importance to efficacy, was largely unknown to the vector control community. Crystallographic characterization of contact insecticide solids needs to be systematic to identify more active solid forms. Here, the investigators report seven new crystal structures, mostly pyrethroid insecticides recommended by the WHO for indoor residual spraying, as well as a new form of a neonicotinoid insecticide. These results further highlight polymorphism in contact insecticides. Find the article here.