Northern corn rootworm larvae occasionally damage fields of first-year corn in Iowa. Rootworms typically have a 1-year life cycle and rotating corn with another crop has been a very successful management strategy to prevent lodging and yield loss from this insect. Unfortunately, some populations of the northern corn rootworm have successfully adapted to the corn-soybean rotation and now have a 2-year life cycle. This 2-year life cycle is called extended diapause because some of the eggs remain dormant in the soil for nearly 2 years before the larvae hatch. For instance, for the eggs that are laid in 1999, some larvae hatch in 2000, but the remainder will not hatch until 2001.