Slippery Barrier Tape. Walnut Caterpillar,/ Cankerworm / Bark Scorpion / + / 30 ft roll Prevents upward migration of caterpillars and Bark Scorpions . Non-Chemical 2" x 30 ft roll protects 25 four-inch trees Applied to the trunk of the tree as a slippery barrier The barrier is too slippery for caterpillars to climb across it. Stops defoliation from migrating caterpillars