North American Wheel Bug (cristatus) North American wheel bugs are highly regarded by organic gardeners because they consume a variety of insects and their presence indicates a healthy, pesticide-free ecosystem. "They're the lion or the eagle of your food web," Dr. Michael J. Raupp, an entomologist at the University of Maryland, notes. "They sit on top. When you have these big, ferocious predators in your landscape, that tells me that this is a very healthy landscape, because all these other levels in your food web are intact." https://en.wikipedia.org/wiki/Arilus_cristatus#Ecological_significance I think it unlikely that they are cause of dying sassafras tree.

https://extension.illinois.edu/blogs/good-growing/2022-10-07-wheel-bugs-good-bugs-painful-bite

D Smith gave a suggestion:  

North American Wheel Bug (cristatus) North American wheel bugs are highly regarded by organic gardeners because they consume a variety of insects and their presence indicates a healthy, pesticide-free ecosystem. "They're the lion or the eagle of your food web," Dr. Michael J. Raupp, an entomologist at the University of Maryland, notes. "They sit on top. When you have these big, ferocious predators in your landscape, that tells me that this is a very healthy landscape, because all these other levels in your food web are intact." https://en.wikipedia.org/wiki/Arilus_cristatus#Ecological_significance I think it unlikely that they are cause of dying sassafras tree.

https://extension.illinois.edu/blogs/good-growing/2022-10-07-wheel-bugs-good-bugs-painful-bite