The western bean cutworm, Striacosta albicosta (Lepidoptera: Noctuidae), is native to North America. It was first reported as a pest of Colorado pinto beans in 1915. In 1935, adults were captured in western Nebraska (Hagen 1963) and later, in 1954, it was identified as a pest of corn in southern Idaho (Blickenstaff 1979). Since its discovery in the late 1880s, it has slowly and steadily expanded its known distribution eastward from Arizona to Iowa (Rice 2000) and Minnesota (O'Rourke and Hutchison 2000). The western bean cutworm was known to occasionally occur in western Iowa prior to 1975, but it was not until2000 that an economically damaging population was found in field corn. Since then, it has become an annual economic pest in western and central regions of the state. In 2004, western bean cutworms were collected in pheromone traps for the first time in Illinois and Missouri.