A North American pest is recognizing that acres and acres of the Corn Belt’s soybean fields could become its next food source as it migrates south from Canada into Minnesota and the Dakotas, with eyes potentially on Iowa soon.

University of Minnesota entomologist Robert Koch said the soybean tentiform leafminer has moved into the Upper Midwest, laying eggs on the underside of soybean leaves that then hatch in the leaves.

As the larvae (caterpillar) lives and feeds within the leaves, it tunnels...