Spongy Moth in Grand Rapids

JPEG image of Spongy Moth caterpillar on a leaf

Spongy moth has been a forest pest in Michigan for over 40 years. Over the last several years, the population and effects of spongy moth have been above average in Grand Rapids. This has mainly affected areas with high oak tree populations.

Steps You Can Take

If you encounter a tree affected by spongy moth, there are a few things you can do to help.

  • Read the Homeowners Guide to Spongy Moth Management(PDF, 1MB) tip sheet
  • Water the tree(s) throughout the summer to help with leaf regrowth
  • Remove egg masses and wrap trees with a barrier
  • Treat the tree(s) with an insecticide like B.t. caterpillar and webworm control
  • Contact a local forester for treatment options. Foresters can be found at the International Society of Arborculture's website
  • Report sightings of spongy moth to 311

Scrape Egg Masses

October through late April

City Forester points to a group of spongy moth egg masses on the trunk of a tree  A close-up image of a spongy moth egg mass

Look for egg masses on tree trunks and scrape them into a cup of soapy water using a plastic putty knife or other dull scraping tool. Egg masses are light brown, sponge-like in appearance and about the size of a quarter.

Watch a how-to video

Apply Tree Bands

Late April through Late May

PNG image of a tap band around a tree to prevent gypsy moth caterpillars from moving up the tree

Just after caterpillars have hatched, when they are small and young, barrier bands will prevent them from climbing back into trees after ballooning or when they have fallen.


Barrier bands can be made using duct tape and/or a waterproof, sticky material such as Tanglefoot insect barrier or petroleum jelly.

  • When the bark is dry, wrap duct tape around the tree, shiny side out, pressing the tape firmly into the bark cracks to prevent caterpillars from slipping under the bands
  • Turn the tape over and wrap once more with the sticky side up. The tape should be wrapped a few inches wide and placed around the tree trunk at chest height (about four feet) above the ground
  • If possible, spread additional sticky Tanglefoot or vasoline onto the lower portion of the barrier.

Watch a how-to video


Watch the following videos:

We haven't determined if a targeted aerial spray treatment is needed in 2023.  

Below are several documents that further explain spongy moth and its treatment:

Want to learn more about spongy moth? Explore additional resources below.