Hello,

The caterpillars and webs you’re observing on your oak tree in Michigan are likely caused by the Fall webworm (Hyphantria cunea), a moth known for its caterpillar stage that creates extensive webbing at the ends of branches. These webs can be up to 2 to 3 feet in length and may contain a colony of hundreds of caterpillars. They are commonly seen on walnut, birch, black cherry, elms, and maples but can also affect oak trees. More information at this link:

What are those large webs in my trees? - Gardening in Michigan (msu.edu)

Here’s what you can do to treat the issue:

Do not burn the webbed branches while they are in the tree, as this can damage the plant more than the caterpillars would.

Trimming out the web is an option if it’s reachable. However, it’s often high up in the canopy. You can consult with a local certified arborist to do this. To find a certified arborist in your Zip Code, go to this link:

Find an Arborist (treesaregood.org)

High-pressure water spray can tear into the nest and kill many caterpillars. Even a garden hose set to high pressure might be effective.

Pesticides can be used if the webs are still small, but the webbing protects the caterpillars, making it difficult for pesticides to reach them. If you decide to use pesticides, tearing the nests with a high-pressure spray first can help the pesticide penetrate.

It’s important to note that by late summer, the damage caused by these caterpillars is usually minimal, as the trees have had time to produce energy reserves for the following season. Most caterpillars will leave the nest to form cocoons in the soil or bark crevices, and the webs will deteriorate over the winter. The caterpillars will not return to the same webs next spring. More information at this link:

What are those large webs in my trees? - Gardening in Michigan (msu.edu)

I hope this helps!