A: First, take a deep breath, then relax. Your plants will come to no long-term harm.
Fall cankerworm and several other common fall caterpillar pests have been worse than usual lately, likely because of the heavy rains of the late summer. They’ll strip leaves off of your trees, which is far from ideal, and make messes everywhere. Some caterpillars leave great big masses of webbing, and some do not. Cankerworms are busy feeding on pecans and hackberries, and we’ve seen pink-striped oak worm on local red oaks.
If the trees are young, spray with either B.T. (Fertilome Caterpillar Killer) or Captain Jack’s Deadbug Brew (spinosad.) If the trees are large and previously in good health, don’t try to spray into the crown of forty-foot trees. It’s impractical!
If your trees are well established and in good health, this damage is considered minor, no matter how unsightly it is. All of those leaves would be coming off in the next couple of months anyway. Repeated stripping of the leaves will stress your trees, but a single season of heavier than normal caterpillar activity will not impact your trees much.