Plants are among many eukaryotes that can “turn off” one or more of their genes by using a process called RNA interference to block protein translation. Researchers are now weaponizing this by engineering crops to produce specific RNA fragments that, upon ingestion by insects, initiate RNA interference to shut down a target gene essential for life or reproduction, killing or sterilizing the insects. The potential of this method is reviewed in Trends in Biotechnology’s upcoming special issue on environmental biotechnology.