Pest

Leafminer Creates Green Bay Packers Colors On Aspen Leaves

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Photo of an aspen leaf that fell in the fall showing a “green island” due to leafminer feeding.

An aspen leaf that fell in the fall showing a “green island” due to leafminer feeding. / Photo Credit: Linda Williams, Wisconsin DNR

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

Most aspen leaves that fell this fall were a beautiful yellow gold color, but every so often some could be found that were yellow with a green strip on them. Were the aspen trees supporting the Green Bay Packers? No. The green stripe was an indication of the presence of a tiny leafmining caterpillar.

Leafminers are tiny caterpillars that live and feed within a leaf. These tiny caterpillars may produce blotch mines or serpentine mines that create lines on the leaf.

Continue reading “Leafminer Creates Green Bay Packers Colors On Aspen Leaves” →

Bronze Birch Borer Attacks Stressed Birch

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

Photo of a white birch tree with its top half dying from bronze birch borer attack.

Bronze birch borer has attacked these trees, and parts of the tree above the attack site are thin and declining. / Photo Credit: Linda Williams, Wisconsin DNR

Bronze birch borer (Agrilus anxius) is a native beetle that attacks birch trees. As adults emerge from the bark, they create small, D-shaped exit holes, similar to emerald ash borer but smaller.

Bronze birch borer attacks stressed trees, and the source of the stress can be anything from drought, flooding, defoliation or old age.

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Please Report Beech Scale Outside Of Door County

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Map showing locations of known moderate or high beech scale populations as of November 2023, in red.

Locations of known moderate or high beech scale populations as of November 2023 are shown in red. High populations are known to be widespread in Door County. / Map Credit: Bill McNee, Wisconsin DNR

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

Earlier this year, we reported that high populations of the non-native insect beech scale (Cryptococcus fagisuga) were identified for the first time in Marinette and Sheboygan counties. Since then, several more sites with moderate or high scale populations have been identified (see map).

Continue reading “Please Report Beech Scale Outside Of Door County” →

Make Your 2024 Spongy Moth Treatment Plans Early

Posted on by akabelowsky
Photo of a finger pointing to a tan-colored spongy moth egg mass on a tree.

A finger points to a tan-colored spongy moth egg mass on a tree. / Photo Credit: Bill McNee, Wisconsin DNR

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

If the 2024 spring and summer weather conditions are favorable for the spongy moth (Lymantria dispar) population, the current outbreak will continue and spread to other parts of Wisconsin. Property owners are encouraged to examine susceptible host trees (including oak, birch, crabapple, aspen and willow) and make plans to manage them.

In summer 2023, Wisconsin saw a record amount of defoliation. State agencies received many calls from property owners urgently seeking a tree care business to control a large caterpillar infestation.

Continue reading “Make Your 2024 Spongy Moth Treatment Plans Early” →

Harvest Timing Affected By Spongy Moth

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Photo showing numerous spongy moth egg masses on an oak tree in Walworth County, Wisconsin

Numerous spongy moth egg masses on an oak tree in Walworth County. / Photo Credit: Bill McNee, Wisconsin DNR

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

Forest managers planning silvicultural treatments in stands susceptible to spongy moth (Lymantria dispar) – such as those containing many host species, including oak, birch, aspen and basswood – are encouraged to conduct annual egg mass surveys before treatment.

Surveys make it possible to predict if heavy defoliation is likely. If more than 30 egg masses are found in a sample area – a circle with a 37-foot diameter – then heavy defoliation is expected in the spring, and management activities should be altered or delayed until an outbreak has ended. Continue reading “Harvest Timing Affected By Spongy Moth” →

Another Ash Pest Found In Northern Wisconsin

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Close-up photo of an adult cottony ash psyllid.

A close-up photo of an adult cottony ash psyllid feeding on an ash leaf. / Photo Credit: Steve Garske, Great Lakes Indian Fish and Wildlife Commission

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

As if black ash trees don’t have enough problems with emerald ash borer (EAB), another ash pest recently was found at several locations in northern Wisconsin.

In June, Great Lakes Indian Fish and Wildlife Commission (GLIFWC) staff noticed black ash with leaf curling and puckering, early leaf drop and dieback at one of their Climate Change Program’s long-term phenology study sites.

After working with DNR Forest Health staff to narrow down the possibilities, insect samples were collected and sent to P.J. Liesch, director of the University of Wisconsin-Madison Insect Diagnostic Laboratory, for official identification. He identified them as cottony ash psyllid.

Continue reading “Another Ash Pest Found In Northern Wisconsin” →

DNR Debuts Video On Scraping Spongy Moth Egg Masses

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Photo of Wisconsin DNR's Andrea Diss-Torrance scraping a spongy moth egg mass off a tree.

Wisconsin DNR invasive forest insects program coordinator Andrea Diss-Torrance demonstrates scraping a spongy moth egg mass off a tree while making a video on the subject for the DNR. / Photo Credit: Wisconsin DNR

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

The fall and winter months present a perfect opportunity to protect trees by searching out and removing spongy moth egg masses.

The invasive insects currently exist only as tiny eggs, camped out in egg masses that can be found in places such as tree trunks and branches, under park picnic benches and swing sets, and under the awnings of buildings.

And now, the Wisconsin Department of Natural Resources (DNR) has debuted a short video showing exactly how to easily and safely remove egg masses to reduce next spring’s population of hungry spongy moth caterpillars.

Continue reading “DNR Debuts Video On Scraping Spongy Moth Egg Masses” →

Look For Spongy Moss Egg Masses

Posted on by akabelowsky

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

Photo of spongy moth egg masses on a tree.

Three spongy moth egg masses are found on a tree branch at Kettle Moraine State Forest Southern Unit in Walworth County. / Photo Credit: Bill McNee, Wisconsin DNR

Now that spongy moth egg laying is complete for 2023, it’s a good time to look for and dispose of the egg masses produced by adult moths over the past two months.

Spongy moth egg masses are tan-colored lumps about the size of a nickel or quarter, and can be found on trees, buildings and other outdoor objects. They may also be found in protected places such as firewood piles and birdhouses.

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Emerald Ash Borer Detected In Rusk County

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By Paul Cigan, DNR Forest Health Specialist, Hayward
Paul.Cigan@wisconsin.gov or 715-634-9232

Photo of an emerald ash borer on a tree

Emerald ash borer was detected in Rusk County in northwest Wisconsin in late July, making it the 69th of Wisconsin’s 72 counties that have confirmed presence of the invasive insect. / Photo Credit: Paul Cigan, Wisconsin DNR

The emerald ash borer (EAB) has been detected for the first time in Rusk County, making it the 69th of Wisconsin’s 72 counties to determine the presence of the invasive insect.

On July 25, Wisconsin Department of Natural Resources Forest Health staff investigated a report of several ash trees with woodpecker flecking and branch dieback in a village park along Railroad Avenue in the Village of Sheldon.

Continue reading “Emerald Ash Borer Detected In Rusk County” →

Spongy Moth Update: State Defoliation Record Set

Posted on by akabelowsky
Photo of spongy moth laying a tan-colored egg mass on an oak tree.

A female spongy moth lays a tan-colored egg mass on an oak tree at the Kettle Moraine State Forest – Southern Unit on July 25. Photo Credit: Bill McNee, Wisconsin DNR

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

In many areas across Wisconsin, conditions were right for the worst outbreak of spongy moth caterpillars (Lymantria dispar) in more than a decade.

The caterpillars of this invasive insect — formerly known as gypsy moth — prefer to feed on oak, birch, crabapple, aspen and willow leaves, but will also feed on many other tree and shrub species. As of early August, caterpillars have pupated, but adult moths remain present.

Continue reading “Spongy Moth Update: State Defoliation Record Set” →