Pest

Web-Spinning Caterpillars Not Spongy Moth

Posted on by akabelowsky

By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov,  920-360-0665

You may already be seeing the web nests created by eastern tent caterpillars, which hatch early in the spring and start feeding on emerging leaves as the weather warms up.

Eastern tent caterpillars can sometimes be mistaken for forest tent caterpillars or spongy moths. Check out the DNR’s comparison fact sheet, which includes pictures for identification and control options. Continue reading “Web-Spinning Caterpillars Not Spongy Moth” →

Columbian Timber Beetle Fact Sheet Debuts

Posted on by akabelowsky
Photo showing staining, in the shape of a many-pointed star, evident in the cut ends of silver maple logs.

Staining, in the shape of a many-pointed star, is evident in the cut ends of silver maple logs. / Photo Credit: Chris Firgens, Oconto County Forest

By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665

Columbian timber beetle (Corthylus columbianus) is an ambrosia beetle native to the eastern United States.

In Wisconsin, we have had reports of Columbian Timber Beetle (CTB) attacking silver maple in the northeastern and lakeshore areas of the state, dating back to the early 1990s. The insects have caused significant staining from repeated attacks. In southern Wisconsin, CTB can attack oaks to a lesser degree, including bur, northern red and white oak.

Continue reading “Columbian Timber Beetle Fact Sheet Debuts” →

UW-Madison’s Raffa Talks Trees’ Natural Defenses

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Photo of Ken Raffa, professor emeritus with the University of Wisconsin-Madison Department of Entomology.

Ken Raffa, professor emeritus with the University of Wisconsin-Madison Department of Entomology. / Photo Credit: University of Wisconsin-Madison

By Art Kabelowsky, DNR Outreach and Communications, Fitchburg
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

Do you pity the poor tree, forced to stand defenseless against the ravages of insect pests, fungi and disease?

Then, you have not listened to Dr. Ken Raffa discuss the impressive natural defenses trees have developed.

Raffa, a professor emeritus with the University of Wisconsin-Madison’s Entomology Department, recently appeared on Proforest Podforest podcast to discuss the topic “Inside the Tree’s Natural Defense.”

Continue reading “UW-Madison’s Raffa Talks Trees’ Natural Defenses” →

2025 DNR Spongy Moth Spray Plans Announced

Posted on by akabelowsky
Photo showing an airplane spraying pesticide over trees at Devils Lake State Park in Sauk County to help in the control of spongy moth caterpillars.

An airplane sprays pesticide over trees at Devils Lake State Park in Sauk County to help in the control of spongy moth caterpillars. / Photo Credit: Sue Johansen, Wisconsin DNR

By Art Kabelowsky, DNR Outreach and Communications
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

The Wisconsin Department of Natural Resources (DNR) has finalized aerial spraying plans for its 2025 Spongy Moth Suppression Program, with maps for the five selected treatment areas available online.

The treatment sites are at three state parks in Juneau, Marinette and Sauk counties that are highly valued for their recreational use. A total of 544 acres of trees will be treated with an aerial spray of “Foray” bacterial insecticide containing Bacillus thuringiensis var. kurstaki.

Continue reading “2025 DNR Spongy Moth Spray Plans Announced” →

La Crosse County Added To Spongy Moth Quarantine

Posted on by akabelowsky
A closeup photo of a spongy moth caterpillar consuming a leaf.

A spongy moth caterpillar consumes a leaf. / Photo Credit: Bill McNee, Wisconsin DNR

By Wisconsin Department of Natural Resources (DNR)

La Crosse County has become the latest Wisconsin location to be added to the state and federal spongy moth quarantine, joining most eastern and central Wisconsin counties already considered to be infested by the invasive insect.

The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) announced the change on April 1, based on trapping data collected last year.

Continue reading “La Crosse County Added To Spongy Moth Quarantine” →

Fight The Bite! Watch For Ticks

Posted on by akabelowsky

By Michael Hillstrom, DNR Forest Health Specialist
Michael.Hillstrom@wisconsin.gov

Ticks are active now, so it’s time to start taking precautions to prevent tick bites and transmission of the diseases they carry. Whenever temperatures at ground level get above 40-42 degrees Fahrenheit, ticks will start to be active.

Continue reading “Fight The Bite! Watch For Ticks” →

Avoid Seedy Hitchhikers This Summer

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A photo showing a large patch of the invasive plant garlic mustard on a wooded property. The aggressive plant spreads and outcompetes native plants and trees for nutrients.

Avoid creating infestations of invasive plants — such as this huge patch of garlic mustard — on your wooded properties; don’t transport or plant aggressive spreaders as you head up north this summer. / Photo Credit: Steven Katovich, Bugwood.org

By Wisconsin Department of Natural Resources (DNR)

Hitchhiking invasive plants, insects and pathogens are worthy of concern.

As you dream of days spent at the cabin up north, planting your garden or wandering in the woods, here are a few reminders to help you avoid bringing hitchhiking invasives along as you enjoy your spring and summer activities.

Continue reading “Avoid Seedy Hitchhikers This Summer” →

Watch For Oak Decline And Mortality This Summer

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Oak decline and mortality at Big Foot Beach State Park in 2024.

Oak decline and mortality at Big Foot Beach State Park in 2024. / Photo Credit: Wisconsin DNR

By Michael Hillstrom, DNR Forest Health Specialist
Michael.Hillstrom@wisconsin.gov

Oak decline and mortality continue to be an issue in Wisconsin, and because of the recent droughts and spongy moth outbreak, we expect these impacts to become more widespread this summer.

Forest decline is the progressive loss of tree and stand vigor and health over several years without obvious evidence of a single causal factor. Typically, trees die in a scattered fashion across a large area over several years. The additional stress from defoliation can result in pockets of heavy oak mortality, particularly on dry, sandy sites and steep, rocky ridges and hills.

Continue reading “Watch For Oak Decline And Mortality This Summer” →

DNR Urges Spring Spongy Moth Treatment Plans

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Carefully scraping spongy moth egg masses off trees and into a cup of soapy water will help to hold down caterpillar damage in 2025.

Carefully scraping spongy moth egg masses off trees and into a cup of soapy water will help to hold down caterpillar damage in 2025. / Photo Credit: Bill McNee, Wisconsin DNR

By Bill McNee, DNR Forest Health Specialist
Bill.McNee@wisconsin.gov or 920-360-0942

The Wisconsin Department of Natural Resources (DNR) encourages property owners to examine their trees for spongy moth egg masses and determine whether control measures are needed this spring.

Property owners who have oak, birch, crabapple, aspen, willow and linden (basswood) trees should be particularly watchful because the caterpillars of this invasive insect prefer these species. However, they will feed on many other kinds of trees and shrubs.

Continue reading “DNR Urges Spring Spongy Moth Treatment Plans” →

Treat Ash Trees Against Emerald Ash Borer This Spring

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A photo of an ash tree next to a park trail in Winnebago County showing damage from woodpeckers feeding on EAB larvae beneath the bark.

An ash tree next to a park trail in Winnebago County shows damage from woodpeckers feeding on EAB larvae beneath the bark. / Photo Credit: Bill McNee, Wisconsin DNR

By Bill McNee, Forest Health Specialist
Bill.McNee@wisconsin.gov or 920-360-0942

Property owners with healthy, valuable ash trees are encouraged to treat them with insecticide this spring to protect against emerald ash borer (EAB).

The invasive pest is currently the most damaging threat to trees in Wisconsin, killing more than 99% of the ash trees it infests.

Continue reading “Treat Ash Trees Against Emerald Ash Borer This Spring” →