The return of rain following the end of El Niño should be good news for farmers in Southern Africa. But a pest from the Americas is ruining everything. Countries recovering from the two-year long drought that caused widespread food insecurity now face a rapidly spreading crop killer. The invasive fall armyworm is destroying maize across the region and spreading quickly from country to country serving a “blow to prospects of recovery” for the region, says the U.N. Food and Agriculture Organization (FAO).