The following question was sent to the P&PDL diagnosticians here at Purdue University:
Question: I read the posting but I am still unclear and partly unhelped. I have a globe locust tree. It is at least twice as high as the roof of my house, so I cannot effectively spray the foliage. How do I stop the webworm--preferably with applications in late Fall or early Spring, on the ground or on the bare bark or both? Or is that impossible? There have been some years in which infestation has not occurred but I cannot determine why. Does tanglefoot around the trunk stop any from moving from the soil to the foliage?
Answer: To answer your questions: The mimosa webworm does not move from the soil - thus the tanglefoot material is not helpful. The insecticide that you spray in the tree will only be effective as high as the spray can be applied and above that the insects will continue to defoliate.