Poor farmers now have a new, low-cost spray to control African armyworm. This devastating pest migrates from Tanzania and Kenya to eastern and southern Africa. Farmers can lose between a quarter to nearly three-quarters of their crops and pastures in armyworm outbreaks. As well as being environmentally friendly, the new spray replaces expensive chemical insecticides. It’s made from armyworms that die when they feed on low-grade pastures sprayed with a virus. Because the dead armyworms are full of the virus, they can then be used to make more spray to kill more armyworms. This can be done locally rather than in far-off factories. Proven in Tanzania, the spray kills armyworm just as effectively as conventional insecticides and is already used in the armyworm control programme there.