A newly identified crystal structure of DDT suggests that reformulating the compound to boost its insecticidal properties may be possible (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201703028). The advance could lead to ways of using DDT more efficiently and in smaller quantities, thereby reducing its broader environmental effects. DDT was developed in the 1940s as an insecticide, and many countries still use it for malaria control. But it is also a persistent organic pollutant that is banned elsewhere because of its toxicity to other species. Since DDT’s discovery, scientists have believed that it had only one crystal structure, dubbed form I. Inspired by a stock micrograph that suggested helical twisting of DDT crystals, a team led by Bart Kahr and Michael D. Ward of New York University has now experimentally characterized a second crystal structure, form II. Computational analysis points to two more possibilities. DDT adsorbs on insects’ hydrophobic footpads when walking on crystals, a first step toward insecticide uptake. So the researchers hypothesized that different crystal structures could influence adsorption. Experiments with Drosophila melanogaster fruit flies indicated that form II is a more potent insecticide than form I, at least for that species.