Several reports have surfaced regarding caterpillars attacking hemp crops, mostly or entirely crops grown for cannabinoids.
From UK extension entomologist, Dr. Ric Bessin: "The insects in the photo are corn earworms, also known as tomato fruitworm, soybean podworm and cotton bollworm. It feeds on many different hosts. We should be able to use the Bt insecticides on hemp. The Bt insecticides are most effective when the larvae are small, those in the photo are large, so expect some reduction in effectiveness. I would suggest a high rate of Dipel, Agree, Javelin, or Xentari to control these corn earworm larvae on the hemp if they are still active."