Fall webworm damage is showing up right now
Looking around at trees in the Miami Valley and my own landscape, I notice a lot of webbing of the foliage due to the fall webworm.
This caterpillar has two generations and despite being named the fall webworm, its first generation usually shows up in late spring, shortly after the Eastern tent caterpillar. Both of these caterpillars create webs to protect themselves from predators.
The Eastern tent caterpillar comes out in early spring, around May in this area, and creates webbed nests in the crotch angles of branches. These caterpillars stay in the nest at night and emerge during the day, or when it is warm at night, to feed on the leaves, returning to the nest.
On the other hand, the fall webworm actually envelopes the leaves in the nest and feeds on the leaves with the protection of the nest surrounding them. They feed in bunches and there will be groups of caterpillars within the nest.
The first generation of fall webworm shows up early in the summer, however, the nests are small and usually unnoticeable. The second generation uses these nests and expands them. They can sometimes encompass large branches of trees.
If you look closely at their nests, you will notice that as they feed and kill a bunch of leaves, they move on to fresh leaves, feeding and building their nests.
Eastern tent caterpillars tend to love cherry, apple, pear, maple, hawthorn and a few other trees. Fall webworm, as you can see by looking around, have a very broad love of plants. I have them on my seven-son tree, hydrangeas, and a wide variety of other deciduous trees.
Both of these caterpillars are really more of an annoyance than anything else. They don’t kill a tree but just feed on the foliage.
In terms of the fall webworm, I mentioned a few weeks ago that leaf damage later in the season is usually no big deal. These leaves will be falling soon eventually.
Populations of the fall webworm tend to be high this fall. I have seen them on quite a few different plants around the area.
The best control, if they really bother you, is to either trim off the nest and smash the caterpillars or use a gloved hand and pull out the nest and as many caterpillars as possible.
Predators and parasites also do a good job of eliminating the nests as well so you can let nature take its course.
There are sprays that can be used on caterpillars if they really bother you, but you have to remove the nest material before spraying. Otherwise, the pesticide won’t penetrate the nest.
Populations of both of these caterpillars rise and fall. While they might look like they are devastating trees, they really don’t do too much damage. I tend to leave them alone.