Corn rootworms have long been major economic pests in the United States. In Pennsylvania, corn rootworm damage has been sporadic, but increasing in recent years.
John Tooker, Ph.D.
Western corn rootworms that developed resistance to some Bt corn varieties may now be a problem in PA.
Farms with continuous corn production, and specifically fields planted to the same Bt year after year, are at most risk for developing resistant rootworm populations.