Caterpillars - Ask Extension
I have huge oak trees in my yard, and this year we have thousands of small, dark caterpillars all over our house, trees, and rose bushes. As you can s...
Knowledgebase
Caterpillars #870821
Asked May 30, 2024, 4:51 PM EDT
I have huge oak trees in my yard, and this year we have thousands of small, dark caterpillars all over our house, trees, and rose bushes. As you can see from the pictures, they have chewed off most of the leaves on the rose bushes, and the oak leaves on the trees. We have had these caterpillars before but there’s never been this many and they never done this much damage. Is there anything we can do?
Calhoun County Michigan
Expert Response
These are spongy moth (formerly gypsy moth). Parts of mid-Michigan are inundated with Spongy moth right now. The bad news is that there's not much to be done to control the issue for the next 2-3 weeks. When the larvae are too large, insecticide efficacy decreases. After those few weeks, they'll pupate and turn into adults.
If you have trees covered with caterpillars, you can set up sticky bands or burlap wraps to catch, collect, and kill the climbing ones. See here for how to do this: https://www.canr.msu.edu/resources/using-bands-to-protect-shade-trees-from-spongy-moth
If your trees are more than 10-15 feet, its unlikely that you'll achieve good coverage without aerial spraying (too late in season for this) or an arborist who has the correct equipment to have the insecticide reach and kill the caterpillars that are high in the foliage.
In August, you'll want to look at tree trunks for evidence of egg masses and scrape those off into soapy water. This will help reduce the numbers that will emerge in the next season.
See here for additional information: https://fyi.extension.wisc.edu/spongymothinwisconsin/pest-management-2/management-guide-for-homeowners/
If you have trees covered with caterpillars, you can set up sticky bands or burlap wraps to catch, collect, and kill the climbing ones. See here for how to do this: https://www.canr.msu.edu/resources/using-bands-to-protect-shade-trees-from-spongy-moth
If your trees are more than 10-15 feet, its unlikely that you'll achieve good coverage without aerial spraying (too late in season for this) or an arborist who has the correct equipment to have the insecticide reach and kill the caterpillars that are high in the foliage.
In August, you'll want to look at tree trunks for evidence of egg masses and scrape those off into soapy water. This will help reduce the numbers that will emerge in the next season.
See here for additional information: https://fyi.extension.wisc.edu/spongymothinwisconsin/pest-management-2/management-guide-for-homeowners/
