Last summer I spent two humid sunsets in a cornfield in Illinois, learning about the corn rootworm–which is not actually a worm, but rather a beetle. It is the most consequential pest in American agriculture. Known as the “billion dollar bug,” its costs to corn growers is estimated at somewhere just shy of 2 billion dollars, including research into GM crops that have kept the pest under control for a decade, but now are starting to fail.

It’s an constant evolutionary battle between farmer, beetle and the ag company scientists trying to help farmers fight it off. The beetle has developed resistance to every pesticide farmers have thrown its way–and to age-old agricultural practices such as crop rotation as well.

Joe Spencer, an entomologist who has devoted his career to studying the bug and is known to his colleagues at the Illinois Natural History Survey, affectionately, as “Cornboy,” gave me a tour of the world of the rootworm, and I wrote about it in Scientific American’s March 2017 issue. I have never seen more corn in my life.