A Cornell University "trap network," begun in 1994 to alert farmers when damaging pests are threatening 60,000 acres of sweet corn across New York state, could now help researchers track how these pests respond to changing climates.

Corn earworm is typically a late-season pest of sweet corn in upstate New York. Earworm adults -- pale brown moths -- migrate north each year, often arriving in mid-August. During the first years of the network, the special pheromone traps set up in July to monitor earworms remained empty for several weeks.

But an unexpected outbreak of earworm in Eden, N.Y., in June 1999 prompted researchers at the New York State Integrated Pest Management (IPM) Program, which is part of Cornell Cooperative Extension, to start looking more closely. Since then, low numbers of earworms -- with occasional spikes in their numbers requiring sprays -- have consistently turned up in traps in western New York from early June until the migratory flight kicks in during August.