Large infestations of wireworms in two separate Massac County fields have been reported this spring, says University of Illinois Extension Entomologist Mike Gray.

“Ron Hines, an independent crop consultant in southern Illinois, reported large infestations of wireworms in two separate fields devoted to no-till corn production in 2010,” Gray says. “Ron placed wireworm bait stations in both fields and after digging up the baits, detected an average of 35 wireworms/trap.”

Gray says the established threshold for wireworms is generally considered to be the detection of 1 wireworm/bait station. If this threshold is exceeded, producers are encouraged to consider the use of a soil insecticide applied at planting, preferably one labeled for an in-furrow placement.

”Rescue treatments are not an option,” he says. “Heavily infested fields often require replanting areas most affected due to significant stand reductions.”

The use of a soil insecticide is encouraged during replant operations, Gray adds. Although insecticidal seed treatments confer some protection against wireworms, intense infestations may overwhelm the ability of seedlings to withstand feeding injury

Prolonged wet soil conditions and cool temperatures tend to enhance the prospects for increased wireworm damage to cornfields. Wireworms will continue to feed in the seed zone as long as soil temperatures remain cool.

U of I has more information online about the life cycle, biology and establishment of bait stations for wireworms.