They're Back!

By Paul James

It looks like it’s shaping up to be a good year for fall webworms…if you’re a webworm, that is. I noticed a nest of them yesterday morning in my black walnut tree, and on the drive to work I spotted at least a half-dozen more elsewhere in the neighborhood. So will this year’s infestation be especially nasty?

It’s hard to say, because the occurrence of fall webworms tends to be somewhat cyclical. A really nasty year – such as we had in 2016 -- is often followed by several years of low to normal infestation, such that you barely even notice the webs.

The culprit is a lovely white moth that goes by the name Hyphantria cunea. The female moth lays her eggs near the tips of tree branches, and within a week or so the eggs hatch and begin feeding – and creating their webs along the way -- as caterpillars. At least 90 species of deciduous trees are affected, but in our neck of the woods fruit and nut trees are especially vulnerable.

So there you have a little background information. Now on to the question on everyone’s mind: What in the world should I do to control these annoying little buggers? And the answer is: Nothing. Repeat: Nothing. The fact is webworms don’t really pose a threat to the trees they infest. Yes, they’re unsightly. And yes, they’re kind of gross. But in the end, they’re pretty much harmless.

You can prune to remove the webs that are within easy reach. You can open the webs with a pole and hope the birds will eat the caterpillars, or spray Bt (Bacillus thuringiensis, a bacteria that only attacks caterpillars) into the opened web. You can, as my grandfather did, light the end of a long, gasoline-soaked pole and burn them out. But most homeowners don’t have pruners long enough or sprayers powerful enough to reach into the canopy of mature trees. And most understand the dangers associated with fire.

So why bother? Why not instead come to terms with the fact that a) the webworms are harmless; b) the leaves of deciduous trees will be falling soon; and c) you’ve got more important things to do with your time.

As for me, that means ignoring the webworms in my hickory tree and focusing instead on planting a fall vegetable garden, where webworms aren’t a problem at all. Of course, I do have an issue with cutworms, but that’s a completely different subject.