Corn Rootworm Beetles (genus Diabrotica)–of which there are three prominent species–are a highly destructive and pervasive insect pest of corn in the U.S. The Western Corn Rootworm (D. virgifera virgifera) and the Northern Corn Rootworm (D. barberi) are the most devastating rootworm species in corn-growing states like Iowa and the more northern states that grow various amounts of corn. A third species, the Southern Corn Rootworm (D. undecimpunctata howardi), also known as the Spotted Cucumber Beetle, is a major economic pest in other regions, and has a wide range of host plants, including cucumbers, soybeans, cotton and beans (and many others). Although these ‘southern’ beetles do migrate north some each year, they are seldom a problem in the more northern areas compared to the western and northern species.
Corn rootworm larvae can destroy significant percentages of corn if left untreated. The USDA has estimated (as of 2011/2012) that corn rootworms cause a yearly loss of approximately $1 billion in lost revenue for corn growers ($800 million in yield loss and $200 million for the cost of control measures to combat them).
Additional Information: Corn Rootworm Beetles (Northern, Western and Southern) (University of Illinois)