In spite of grower claims to the contrary, continuous corn often incurs a measurable yield reduction, compared to corn that follows soybeans, or other legume crops, in rotation.  Long term research data, from several researchers, shows about a ten percent yield reduction for continuous corn, compared to corn-following-soybeans.  The amount of yield reduction is highly variable but consistent in its occurrence.  [Paragraph] Several factors have been cited for their contribution to continuous corn yield reductions.  These include insects, plant pathogens, changing weed spectrum, nutrient shortages, and soil structural or drainage issues.  Since so many factors contribute to potential yield reduction in continuous corn, it is nearly impossible to quantify the individual contribution of each factor.  Tillage or no-tillage choices may have the largest impact on continuous corn performance, resulting in both direct and indirect effects on the corn crop. [Paragraph] Insects and plant diseases are noted sources of yield reduction when conditions favor these pests.  Of the common insects associated with continuous corn, the corn rootworm is regarded as having the largest overall impact.  The European corn borer is another insect that has potential to increase with no-till continuous corn.  Various insects with potential to affect continuous corn performance are discussed in light of risk to the crop.