Coping With Webworms
First things first. Pecans and caterpillars have co-existed for thousands of years. These fall webworms aren’t going to kill your trees. So, sleep better tonight.
However, if you value the good looks of your landscape in fall, you’re going to take some measure of control of these pests before they get out of hand. They start by tying a few leaves together to form their protective webs. Then they set out to conquer the world. Within just a few days the webs will have grown from saucer-sized colonies to 3-foot-long cities of caterpillars. Within a week or two more they can completely engulf entire trees. In a word, by that time they’re really ugly.
Trim them out. That’s all you have to do. Trim them out early, before the webs become massive. Use a long-handled pole pruner (stay away from power lines). Nip out those first signs of web formation by trimming off the tips of the branches. Since you’ll just be cutting small twigs, it won’t hurt the tree, and it will eliminate the unsightly worms. As we said for eastern tent caterpillars this spring, spraying for these pests way up in tall trees is simply inefficient. Pruning is the only good way to control them. (Try not to have too much fun!)