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Streets & Urban Forestry

Spongy Moth Resources for Residents

On this page you will find:

Resource Guides

Spongy Moth Resource Center

The State of Wisconsin Department of Natural Resources and the Department of Agriculture, Trade, and Consumer Protection along with the University of Wisconsin-Madison Extension created this thorough spongy moth resource. 

They also have a hotline at 1-800-642-6684

You can email them questions at spongymoth@wisconsin.gov

 

UW-Extension Guide for Homeowners

This is a season-by-season guide on how to care for your trees in response to the spongy moth.

 

Dane County Office of Energy and Climate Change - Spongy Moth Information

A webpage compiled by Dane County with resources and photos.

 

Certified Arborists

A link to the Wisconsin Arborist Association so you find a certified arborist if you want more help to care for the trees on your property.

 

Watering and Mulching

Doing this helps your tree recover from spongy moth caterpillars and is also just a good idea for your tree. Think of your tree like a person. You want to be sure they have plenty of water, especially when they are sick.

 

Watering Your Tree

The general rule is that if the soil feels dry then the tree likely needs water.  According to the Arbor Day Foundation, trees need 10 gallons of water for each inch of the trees diameter - but you have to be careful not to over water the tree, too.

Tree Watering Resources

 

Mulching Your Tree

Mulching correctly helps your trees retain moisture, moderates soil temperatures, and prevents soil compaction. Mulching the wrong way can be harmful. 

You want your mulch to be about 2 to 4 inches deep, and you do not want to mound it up higher near the tree. In other words, do not create "mulch volcanoes." 

Mulching Resources

Burlap Trap Bands

From the late spring into August, you can wrap a burlap band around the trunk of your tree to prevent caterpillars from crawling into the canopy and eating leaves.   

Remove the bands in August after the moths have started laying egg masses. 

How to Video

Watch the Wisconsin DNR video that shows the steps on how to appropriately install a burlap band and what to do with the caterpillars once you trap them.

Burlap Trap Band Steps

  1. Wrap

    Wrap a 20-inch wide (or so) band of burlap completely around the trunk of your tree at around chest height from the ground.

  2. Tie

    Use rope or twine to tie the burlap band to the tree.  Position the rope or twine so it is in the center of the band.

  3. Fold

    Fold the top 6 inches of the band down so it flops toward the string.

    You are creating a trap where caterpillars from the ground cannot crawl up into the canopy to eat the leaves of your tree.

  4. Check Daily

    Check the burlap band every afternoon for caterpillars.  Yes, this is a daily task.

    Scrape any caterpillars you find into a jar of soapy water to drown them.  Discard the dead caterpillars into the trash. 

Destroy Egg Masses

From the fall through until the spring, you can destroy spongy moth egg masses.  Each mass can contain 1,000 individual eggs, so destroying them helps control the population. 

Egg masses look like fuzzy brown patches. They can be found on tree trucks, under tables, along sheds, on RVs, and any other flat outdoor surface.  Here is a zoomed in photo of what egg masses look like:

Spong moth egg masses on the underside of a tree branch.
Image credit: Wisconsin Department of Natural Resources

The masses are too strong to squish, so you have to use one of these options.

Golden Pest Oil / Horticultural Oil

This is a natural soybean oil that can sometimes be found in garden centers, though it may be hard to find in small amounts for homeowners.  

Use this oil as directed to spray onto the egg masses.  You must use it as directed in order.

Scrape - Soak - Trash

The Wisconsin Department of Natural Resource has a short video to show you how to do this yourself.

You will need a putty knife, or a similar tool flat-edged tool.  You will also need a jar filled with soapy water.

  1. Scrape

    After you find the egg mass, use a putty knife or other flat-edged tool to carefully remove the egg mass.  

    Drop it into soapy water.

  2. Soak

    Let the egg masses soak for 24 to 48 hours so they become completely water logged.

  3. Trash

    Put the soaked egg mass into the trash.

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