Have you seen the Halloween decorations in some of our deciduous trees, particularly the walnuts? Perfect webs that look like someone has decorated early are quite showy.
These webs are housing the second generation of fall webworms and are not a big deal for the trees. They may annoy you, but the trees will survive.
Fall webworms, unlike their name, hatch in late spring with the first generation of caterpillars. Their feeding is hardly noticeable, and they don’t construct the webs that are visible now. No one sees them unless they are specifically looking for them.
The second generation hatches and begins to construct their web-like nest. The silken strands surround the foliage at the ends of the branches which makes them visible. These nests are protective and difficult to penetrate with pesticides sprays.
They feed on the foliage of preferred plants inside of the nest, continuing to envelope more leaves as needed. They are harmless and won’t kill a tree.
Since it’s so late in the summer season, and the leaves will be dropping soon, no need to worry. However, hand-removal of the nest is possible, particularly if they really bother you. The challenge with this is that they tend to be higher in the tree than you can reach!
I remember my dad taking a rag and wrapping it around a stick and burning the nests. I have heard many tell me that their parents and grandparents did this. It worked, but is not a recommended practice!
You can take a rag and wrap around the stick and remove as much of the nest as possible or you can trim the end of the branch and eliminate the nest. Dropping the caterpillars in soapy water kills them.
Again, they are more annoying than anything else. They won’t kill the tree!
In addition, I noticed that populations this season are much lower than last year. Last summer was a banner year for them. I couldn’t find a walnut tree that didn’t have several nests.
It will be interesting to see what next year brings in terms of populations. Beneficial insects follow pest outbreaks and build in populations. Eventually, the bad guys decline and the beneficial insects increase.
It’s kind of like an up and down roller coaster. The bad guys grow, the good guys follow, the bad guys decline, the good guys follow. And so goes nature. I love it!
The point is, this is an insect that really isn’t a big deal in our landscapes and can be left alone. It may look bad, but it won’t hurt the tree.
If you have fall webworm nests, observe the numbers this year and see what happens next year. That’s what I am doing!
Pamela Corle-Bennett is the state master gardener volunteer coordinator and horticulture educator for Ohio State University Extension. Contact her by email at firstname.lastname@example.org.