Iowa has been slowly accumulating degree day temperatures in 2013; the state is about four weeks behind 2012. About 10 percent of common stalk borer larvae can begin moving to corn after accumulating 1,300-1,400 degree days (base 41 degrees F). This week, some parts of southern Iowa reached this important benchmark (Fig. 1). Scouting for migrating larvae in corn should begin this week to make timely treatment decisions.