The European corn borer, Ostrinia nubilalis (Hübner), significantly affects production of Zea mays L. (field corn, popcorn, seed corn, and sweet corn), as well as other crops, including sorghum, cotton, and many vegetables. Overall, yield losses and control expenditures associated with the European corn borer cost farmers in the United States more than 1 billion dollars annually.

The European corn borer is an introduced insect species that belongs to the family Pyralidae in the order Lepidoptera. It probably arrived in North America during the early 1900s in broom corn imported from Hungary and Italy for the manufacture of brooms. First noticed near Boston, Mass., in 1917, the European corn borer also was found later, in 1921, in areas bordering Lake Erie. It spread gradually from southern Michigan and northern Ohio. By the end of 1938, it had spread only as far west as the Wisconsin shore of Lake Michigan.

During its early history in the United States, the European corn borer produced one generation per year. By the late 1930s, a two-generation per year population appeared in the eastern and north central states. This two-generation per year European corn borer spread rapidly and soon became dominant in the central Corn Belt. It reached Illinois in 1939, Iowa in 1942, Nebraska in 1944, and South Dakota in 1946. Meanwhile, the single-generation European corn borer spread northward into northern Minnesota, North Dakota, and the Canadian provinces of Quebec, Manitoba, and Saskatchewan.

Later, three- and four-generation per year populations of European corn borer appeared in the south along the Atlantic Coast and southwestward in Missouri, Arkansas, Kansas, Oklahoma, and the Gulf states.

Figure 1. Approximate distribution of European corn borer annual generations in the United States and Canada.

The insect has continued to spread throughout the corn growing areas of the United States. In the 79 years since being discovered, the European corn borer has spread northward into Canada, westward to the Rocky Mountains, and southward to Florida and New Mexico. It is now present in all but the seven most western continental states. The figure above shows the approximate current range of the European corn borer in the United States and Canada.