DNR Participates In Beech Leaf Disease Detection Survey

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Map of Wisconsin

A Wisconsin map showing results of a beech leaf disease survey that ran from 2023 to 2026. / Graphic Credit: Wisconsin DNR

By Art Kabelowsky, DNR Forest Health Communications, Fitchburg;
Arthur.Kabelowsky@wisconsin.gov; 608-335-0167

To date, there have been no confirmed discoveries of beech leaf disease (BLD) in Wisconsin landscape, and we are on the lookout for this disease.

The disease is primarily found on American beech (Fagus grandifolia) but can also be found on ornamental species like European, Oriental, and Chinese beech (F. sylvatica, F. orientalis, and F. engleriana). Although it has not yet been found in Wisconsin, recent discoveries of the disease in Michigan and other states highlight the continued importance of monitoring BLD’s expansion.

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Avoid Ash Trees When Scouting For Deer Stand Locations

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A hunter climbs into a tree stand.

A hunter prepares to safely climb into a tree stand. Hunters are advised to stay away from ash trees when choosing a tree to use for their stand, due to the possibility of hidden damage to the tree due to emerald ash borer. / Photo Credit: Wisconsin DNR

By Wisconsin DNR

As deer hunters begin to scout for suitable tree stand locations, the Wisconsin Department of Natural Resources (DNR) warns hunters to avoid placing their deer stands in or near ash trees.

That’s because of the scourge of emerald ash borer (EAB), which has been confirmed present in all 72 Wisconsin counties. It has already left most ash trees in the southern half of Wisconsin dead or dying, along with many in Door County and the Mississippi River counties.

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Tips For Identifying Asian Longhorned Beetle And Lookalikes

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Closeup of female Asian longhorned beetle.

A female Asian longhorned beetle has a shiny appearance, bright spots and black-and-white striped antennae. / Photo Credit: Bugwood.org

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

More than 300 species of longhorn beetles inhabit the Midwest. The invasive Asian longhorned beetle (ALB) is not yet one of them, with no Wisconsin populations reported.

But ALB’s potential for damage is great enough that state agencies are asking members of the public to be on the lookout for the insect — and to avoid being confused by a relative lookalike.

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Species Spotlight: Japanese Stilt Grass

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Wide view of a patch of Japanese stilt grass.

A dense patch of Japanese stilt grass growing within a forest. / Photo Credit: Wisconsin DNR

By Carter Hellenbrand, Invasive Plant Field Specialist, Fitchburg;
Carter.Hellenbrand@Wisconsin.gov

Note: This is the fourth installment in the Forest Health News “Invasives Spotlight” series, a monthly series of Forest Health News articles.

What has stilts, is green in the summer and reddish-purple in the fall? Japanese stilt grass!

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Aspen Leaf Beetle Defoliation Found In North

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Closeup of beetles, and a cluster of eggs, on an aspen leaf.

Young larvae of aspen leaf beetle feed on the undersides of aspen leaves. The arrow points to the cluster of eggs that produced the larvae. / Photo Credit: Wisconsin DNR

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

Aspen leaf beetles have recently been spotted defoliating young quaking aspen trees in Vilas and Oneida counties.

Both adults and larvae will feed on aspen leaves. The defoliation level detected was light to moderate.

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Pine False Webworm Uncommon In Wisconsin

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Messy webbing filled with frass (droppings) and pieces of needles are signs of pine false webworm feeding on this young white pine. The arrow points to a pine false webworm larvae. / Photo Credit: Wisconsin DNR

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

Pine false webworm (Acantholyda erythrocephala) is not a very common insect in Wisconsin, though it is present. They prefer to feed on white pine in Wisconsin, though reference materials say they will also feed on red pine, jack pine and Scotch pine.

Damage was reported as “minor” in the central part of the state from 1953 to 1961. Later, in 1995, 1997, 2002, 2004 and 2006, it was once again observed as a minor pest feeding on red or white pine in the central part of the state, particularly Portage, Waupaca and Waushara counties. In 2024 and again this year, a few scattered young white pine were observed being significantly defoliated in Oneida and Vilas counties.

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Japanese Beetle Populations Still Building In The North

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Beetles feeding on a basswood leaf.

Japanese beetles defoliating a basswood leaf. / Photo Credit: Wisconsin DNR

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

The Japanese beetle (Popillia japonica) is an invasive insect that feeds on many plant species. The adult beetles “skeletonize” leaves by eating the material between the veins.

Adult Japanese beetles feed on the flowers and leaves of more than 300 plant species, including trees, shrubs and herbaceous plants. Forest trees can be defoliated, with open-grown or edge trees suffering the highest defoliation rates.

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Spruce Budworm Hits Hemlock And Tamarack

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Closeup of hemlock branches showing missing and damaged needles.

Hemlock branches show missing needles, and needles with feeding damage, as the result of spruce budworm infestation. / Photo Credit: Wisconsin DNR

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

Spruce budworms are finished feeding for the year, but the damage is still being noticed. That’s especially true in areas where defoliation was severe, such as northeastern Oneida County and southeastern Vilas County.

Spruce budworm prefers to feed on balsam fir and spruce, but in areas with very high populations and severe defoliation, they will also feed on hemlock and tamarack.

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Tamaracks Busy Refoliating After Larch Casebearer Defoliation

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Wide view of stand of trees

Tamarack trees showing the effect of larch casebearer defoliation. / Photo Credit: Wisconsin DNR

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

Earlier this spring, scattered areas of tamarack in North Central and Northeastern Wisconsin showed tan or light brown foliage. Sometimes that is due to frost, but this year it was the work of an insect called larch casebearer.

As the foliage started to expand this spring, the larch casebearer became active and began to feed. The tiny caterpillars mine out the needles of tamarack and use them as “cases” to protect themselves, thus their name.

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Forest Health Staffers Plan Public Appearances

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Two DNR workers discuss tree issues in the forest.

Alex Hornung, Wisconsin DNR Forest Health specialist for Central Wisconsin, discusses the tree disease phomopsis with Chief Forester Heather Berklund during a site visit near Minocqua in July 2026. / Photo Credit: Wisconsin DNR

By Art Kabelowsky, DNR Forest Health Communications, Fitchburg;
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

Alex Hornung, the Wisconsin Department of Natural Resources Forest Health Specialist for Central Wisconsin, will discuss oak wilt biology at a workshop this month.

Hornung will take part in a Wisconsin Forestry Center/Wisconsin Natural Resources Foundation workshop on oak wilt biology and management, focused on information for landowners and the public. The discussion will take place from 1 to 3:30 p.m. Tuesday, Aug. 18, at Schmeeckle Reserve, 2419 N. Point Drive, Stevens Point. She will be joined by Dr. Holly Petrillo, Professor of Forestry at the University of Wisconsin-Stevens Point.

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