Iowa producers may have a new pest to contend with in alfalfa. On July 29, Joel DeJong, ISU field specialist-crops, and I visited an alfalfa field near LeMars that had large populations of “black” aphids as reported by Peter Westra and Todd Russ (LeMars Agri-Center, LeMars, Woodbury County). The field was suffering from drought stress and small populations of aphids were fairly easy to find. Hal Tucker (Tucker Consulting, Storm Lake) also has reported finding alfalfa fields with black aphids covering entire plants in northwestern Iowa
