KEEP OR KILL?
A friend called recently to ask for our opinion on a backyard situation. A large number of caterpillars were descending from webs in a tree and nibbling on his plants. He called in a tree expert who recommended that the offending tree be cut down and removed. Was this truly the only way to manage the problem?
Happily, we could tell him to do nothing: keep the tree, and not to worry about the plants. The caterpillars are Fall Webworms, whose webs start showing up in late summer.
The parents are pretty little white moths. They are native to the US; highly prolific, they lay their eggs in sunny spots on a large variety of host trees. The eggs hatch into the “worms” which weave the nest (same as silk worms). The nests protect them from predators, but they must come out to eat more leaves.
As it is late in the growing season, the leaves they eat have already done their photosynthetic job and losing some of them to the webworms is no real loss to the parent plant. Many of the caterpillars will in turn become food--for birds and predator insects who need the protein for migrating or overwintering.
So, just let them be.
Sadly, the people who don’t know about all this may be spraying, pruning, or even chopping down a whole tree. Compare that to what a few little caterpillars can do.
Note: Our last tip mentioned that milkweed doesn’t provide resources for anything but Monarch butterflies. This is not true, there are a large number of butterflies, bees and insects that benefit from milkweed, and I was quickly brought to task by some of our well informed readers, many thanks to them. Here’s more https://www.xerces.org/wp-content/uploads/2008/06/Wings_sp11_milkweed.pdf