European corn borer populations in Pennsylvania and the value of Bt corn

European corn borer (ECB) has traditionally been a major economic pest of corn throughout the United States. Yearly losses from ECB injury have been estimated as high as $35 million in the Northeastern US, and $1 billion across the country. Recently it has become clear that ECB populations are declining across the Midwest US, and this decline has been attributed to widespread adoption of Bt traits for control of ECB. We assessed ECB populations and the economics of growing Bt and conventional hybrids at 16 sites across Pennsylvania’s four maturity zones and compared them to previous records to determine if ECB populations are similarly declining in Pennsylvania. In 2010, conventional corn varieties averaged 0.12 larvae per stalk, and 0.46 tunnels per stalk across all sites. At sites common between our study and a study from ten years ago, most ECB populations appear to have decreased substantially, but at least one site had populations that appear unchanged. Yield and profit did not correlate well with ECB injury likely because ECB populations were so low; therefore, economic differences are attributable to seed costs, disease and other environmental factors. Our results appear to indicate that farmers in some parts of the state may have an opportunity to improve profitability by growing conventional hybrids.