According to Maine.gov, browntail moths will voraciously devour your lovely leafy trees and flowers. They find fruit trees especially tasty. Oh, and they give you a miserable rash with their poisonous hairs.

If you see a web cut it out of the tree and soak it in a bucket of soapy water, don't just leave it on the ground. After removing the nest give the tree some extra love with fertilizer and a good watering.