Pests

Keep It Local When Stocking Up On Firewood For Winter

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Photo of a firewood stand at Potawatomi State Park

A stand at Potawatomi State Park offers local firewood for sale to campers. / Photo Credit: Wisconsin DNR

By Wisconsin DNR

With the onset of autumn, many Wisconsinites have been making plans to stock up on firewood for the winter.

With that in mind, the Wisconsin Department of Natural Resources (DNR) is reminding residents and visitors about the year-round importance of obtaining firewood from local sources — whether it’s to heat your home in the winter or build a campfire in the summer.

The message is important enough that October has been designated National Firewood Month, and the DNR offers a webpage to explain firewood regulations, best practices and the reasons behind those guidelines.

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Cottony Ash Psyllid Found In Additional Areas

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Closeup photo showing how cottony ash psyllid nymphs feed on the lower sides of leaves and grow white wool over themselves for protection.

Cottony ash psyllid nymphs feed on the lower sides of leaves and grow white wool over themselves for protection. / Photo Credit: Wisconsin DNR

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

Cottony ash psyllid (Psyllopsis discrepans) was observed in 2023 in several areas in northern Wisconsin. Additional sites were then identified in 2024 and this year.

Some provinces in Canada have observed that psyllid numbers can explode during dry periods, so that may be why we started to see some issues in Wisconsin in 2023.

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Hail Damage Can Cause Dieback, Whole-Tree Mortality

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Photo of a young aspen showing signs of severe impact from hail. Arrows indicate each point of impact.

A young aspen shows signs of severe impact from hail. Arrows indicate each point of impact. / Photo Credit: Wisconsin DNR

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

Several high-impact storms across the state this summer have pummeled trees with hail. The photos accompanying this article show the kind of damage hail can bring to forests.

The initial damage following a significant hailstorm can immediately appear severe. But give it a month or two, and the damage can look even more pronounced.

Pines in particular will start to turn varying levels of brown, depending on the amount of damage they sustained. Damage to the branches and twigs is not limited to just the spot where the hail hit. As the summer goes on, damaged areas of bark that were cracked by the hail impact will often split open further and allow more drying and additional separation of the bark from the wood, which kills that area of the branch.

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Fall Webworm Spins Its Way To Attention

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Photo of fall webworms form a tent on a tree at Kohler-Andrae State Park in September 2025.

Fall webworms form a tent on a tree at Kohler-Andrae State Park in September 2025. / Photo Credit: Wisconsin DNR

By Bill McNee, DNR Forest Health specialist, Oshkosh
Bill.McNee@wisconsin.gov, 920-360-0942

The native insect known as fall webworm (Hyphantria cunea) has been generating calls and emails from curious property owners over the past few weeks.

The caterpillars don’t draw much attention on their own; instead, what catches the eye at this time of year are the large webs (or “tents”) that they create on the tips of tree branches.

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Imported Willow Leaf Beetle Spotted

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Closeup photo of an imported willow leaf beetle adult and larva.

An imported willow leaf beetle adult and larvae. / Photo Credit: Wisconsin DNR

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

Imported willow leaf beetle (Plagiodera versicolor) is a small, shiny, blue-black beetle as an adult, and the larvae are small, solid black and spikey. Both feed on the foliage of willow and poplar species. Two generations per year are possible.

The invasive pest was first detected in the United States in 1915, likely coming from eastern Europe.

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Introduced Pine Sawfly Found On White Pine

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

Photo of an introduced pine sawfly larva.

Introduced pine sawfly larva. / Photo Credit: Wisconsin DNR

The introduced pine sawfly was first found in the United States in 1914 and was first detected in Wisconsin in 1944.

Introduced pine sawfly larvae prefer feeding on white pine needles, although literature says they can also feed on jack pine, red pine and scotch pine. Larvae often feed singly, rather than in groups (like redheaded pine sawfly or European pine sawfly do). Larval sawflies can look like caterpillars, but these larvae develop into adult sawflies, which look like a fly or a chunky wasp.

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White Pine Weevil Damage Is Easy To Spot

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A photo showing that white pine weevil has attacked and killed the terminal leader on a young white pine.

White pine weevil attacked and killed the terminal leader on a young white pine. / Photo Credit: Wisconsin DNR

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

 Symptoms of white pine weevil attack are easily detected at this time of year, as damaged leaders turn dark brown and branch tips can curl or droop.

White pine weevil (Pissodes strobi) is a native insect that can attack and kill the terminal leader of white pine, jack pine and spruce. Another common name for this insect is “tip weevil.”

These insects prefer to attack stout terminal leaders.

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Native Sawyer Beetles Resemble Asian Longhorned Beetle

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An adult Asian longhorned beetle, left, and an adult whitespotted sawyer beetle, right. The arrow shows the white spot at the top of the whitespotted sawyer beetle’s wing covers, indicating it’s the native beetle and not Asian longhorned beetle. / Photo Credits: Left, Bugwood.org; right, Wisconsin DNR

Two closeup photos show the similarities and differences between an adult Asian longhorned beetle, left, with spots all over its back and striped antennae; and an adult whitespotted sawyer beetle, right, with one white spot beneath its head and between its wings.

By Michael Hillstrom, DNR Invasive Forest Pest Coordinator
Michael.Hillstrom@wisconsin.gov

More than 300 species of longhorn beetles inhabit the Midwest. The Wisconsin Department of Natural Resources (DNR) posted about one species, the invasive Asian longhorned beetle (ALB), on social media in early July.

Forest Health staff received many photos of potential ALB as a result. Fortunately, none of the photos were of ALB – which has yet to be detected in Wisconsin.

By far, the most common insect seen in the submitted photographs was a native longhorn species called the whitespotted sawyer beetle (Monochamus scutellatus), also known as a pine sawyer beetle.

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Monitor Your Trees For Spongy Moth-Related Decline And Mortality

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A photo taken June 20, 2025, shows dead and dying oaks near Whitewater Lake in Walworth County, following a period of defoliation and summer drought.

A photo taken June 20, 2025, shows dead and dying oaks near Whitewater Lake in Walworth County, following a period of defoliation and summer drought. / Photo Credit: Wisconsin DNR

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

Property owners are encouraged to monitor their trees for signs of decline and mortality, as the last few years have been marked by drought and spongy moth defoliation.

Landowners who have oak, birch, crabapple, aspen, willow, tamarack and basswood (linden) trees should be particularly watchful, because the caterpillars of this invasive insect prefer these species. Many other tree species are not preferred by the caterpillars and are less likely to be heavily defoliated, but are more likely to die if heavy defoliation should happen.

This article focuses on oak impacts.

The 2021-24 spongy moth outbreak has now collapsed statewide; no defoliation has been observed as of late July 2025. Only a few reports of single caterpillars were received by Wisconsin DNR Forest Health staff. (Note: Parts of Wisconsin may be experiencing a continuing outbreak of different caterpillars known as “oak leafroller” and “larch casebearer.”)

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Avoid Ash Trees When Placing Deer Stands

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Photo showing a Wisconsin hunter climbing into his tree stand.

A Wisconsin hunter climbs into his tree stand. The Wisconsin Department of Natural Resources urges hunters to avoid placing their stands on or near ash trees because the trees may experience breakage of stems or branches due to damage from the emerald ash borer. / Photo Credit: Wisconsin DNR

By Wisconsin DNR

It’s time for deer hunters to begin scouting properties to identify potential locations for their deer stands this hunting season.

The Wisconsin Department of Natural Resources (DNR) cautions hunters to avoid placing deer stands in or near ash trees – a practice that presents a clear safety hazard.

Most ash trees in the southern two-thirds of Wisconsin are dead or dying due to the emerald ash borer (EAB), and infestations in the northern part of the state are rapidly expanding. Some areas already experience decline and mortality of ash trees. EAB has been confirmed present in all 72 Wisconsin counties, and unreported infestations are also likely to be present.

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