Fall Webworms in the Organic Garden

Posted by Jamie McIntosh Aug 27, 2009

Every year, I’ve noticed the same caterpillars arrive to commit their ugly ritual of building messy web tents in our walnut and hickory trees. These fuzzy white worms are prolific, dropping their frass (poop!) and sometimes each other on the ground from their nests of hundreds of specimens.

Now that I have a caterpillar field guide, I quickly discerned that these common invaders are fall webworms. They build their protective web nests at the end of branches, where they strip all foliage on their way to becoming a fall webworm moth. My sons had fun throwing sticks and rocks at these nests, and this isn’t too far off from an organic cure. Gardeners can prune these nests from the trees, stopping the defoliation and preventing the next generation of moths from maturing. Burn the nests or sprinkle bacillus thuringiensis on them and dispose of them.