Western and northern corn rootworm are major corn pests in Iowa and surrounding states(Photos 1 and 2). Farmers have seen several management changes, including the release offour Bt-rootworm traits to suppress corn rootworm larvae since 2003. Although bothspecies are persistent pests, western corn rootworm is particularly adaptable. TheGassmann Lab at Iowa State University (ISU) has confirmed western corn rootwormresistance to all Bt rootworm traits in Iowa.