Spongy moth caterpillars - Ask Extension
I live on a 4 acre wood lot. I have been inundated with spongy moth caterpillars which are defoliating my oak trees. They are also climbing all over t...
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Spongy moth caterpillars #871274
Asked June 03, 2024, 11:09 AM EDT
I live on a 4 acre wood lot. I have been inundated with spongy moth caterpillars which are defoliating my oak trees. They are also climbing all over the house and making a general mess. Every day my driveway is covered with a new layer of shredded leaves and round black beads which you can hear raining down in the woods. I’ve lived here 7 years and first noticed a few cut leaves on the driveway last year but nothing like this.
My fear is it’ll just keep getting worse and I’ll lose my trees. Should I be calling in a company to start spraying?
Saginaw County Michigan
Expert Response
Hello Scott
We are getting many questions like yours right now. Here is MSU Entomologist David Lowenstein’s advice from a few days ago:
“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/
(end quote)
I am including the International Society of Arboriculture site to help you find certified arborists in your area: http://www.treesaregood.org
Healthy, large deciduous trees can survive defoliation. If we have a drought this summer or fall (more than 2 weeks with no projected rainfall) give as many of your valuable landscape trees as you can a deep watering. If the season is long enough, trees will push out some new leaves from dormant leaf buds.
We are getting many questions like yours right now. Here is MSU Entomologist David Lowenstein’s advice from a few days ago:
“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/
(end quote)
I am including the International Society of Arboriculture site to help you find certified arborists in your area: http://www.treesaregood.org
Healthy, large deciduous trees can survive defoliation. If we have a drought this summer or fall (more than 2 weeks with no projected rainfall) give as many of your valuable landscape trees as you can a deep watering. If the season is long enough, trees will push out some new leaves from dormant leaf buds.
