Southern WI Forest Health

Frost’s Bite: How Do Insects Survive Winter?

Posted on by akabelowsky
An emerald ash borer larva overwinters by curling into a J shape inside a channel in an ash tree in Brookfield in 2019.

An emerald ash borer larva overwinters by curling into a J shape inside a channel in an ash tree in Brookfield in 2019. / Photo Credit: Bill McNee, Wisconsin DNR

By Michael Hillstrom, DNR Forest Health Specialist, Fitchburg

Michael.Hillstrom@wisconsin.gov

As winter’s chill persists, Wisconsin Department of Natural Resources (DNR) Forest Health staff members are often asked how cold it needs to get to kill insects, especially invasives.

The answer varies from species to species, but many insects are well adapted to dealing with freezing winter temperatures. Some, such as monarchs, avoid the issue and migrate south for the winter. Others, such as multicolored Asian ladybeetles, annoy us with their presence in our homes and offices as they try to avoid the cold until spring.

Continue reading “Frost’s Bite: How Do Insects Survive Winter?” →

What Are Those White Fluffies On Trees?

Posted on by akabelowsky
Lots of beech scale, covered in white wool, makes this tree’s bark look fluffy.

Lots of beech scale, covered in white wool, makes this tree’s bark look fluffy. / Photo Credit: Linda Williams, Wisconsin DNR

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

Last month, we introduced readers to the woolly alder aphid, which is easier to spot in the winter as the insects congregate on alder branches and grow strands of white, waxy material to cover themselves for winter.

But there are other white, fluffy things that you might notice on tree bark or branches as well.

Beech scale, the insect associated with beech bark disease, is covered in white wool and remains on the tree throughout the winter. In areas with high beech scale populations, the beech trees can be so white with insects that the bark looks white, like a birch.

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Woodpecker Flecking On Ash Means EAB

Posted on by akabelowsky
Photo showing that woodpecker flecking on green ash and white ash, from birds feeding on emerald ash borer larvae, will often be extensive and very noticeable.

Woodpecker flecking on green ash and white ash, from birds feeding on emerald ash borer larvae, will often be extensive and very noticeable. / Photo Credit: Linda Williams, Wisconsin DNR

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

Ash trees that are flecked by woodpeckers will have the outer layers of their bark chipped off by the birds. Woodpeckers do this to punch through the remaining bark more easily to get at the tasty emerald ash borer (EAB) larvae living there.

Flecking usually starts at the top of the tree, providing a sure sign that insects are under the bark. Although the problem could be caused by ash bark beetles, the more common culprit is EAB.

Continue reading “Woodpecker Flecking On Ash Means EAB” →

Impacts Of Winter Weather On Trees

Posted on by akabelowsky
A photo showing that heavy, wet snow can bend and deform small trees and cause branch breakage or whole tree failure of larger trees.

Heavy, wet snow can bend and deform small trees and cause branch breakage or whole tree failure of larger trees. / Photo Credit: Wisconsin DNR

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

Winter damage can significantly impact the health of trees. Keeping trees healthy through the fall is important for reducing winter stress. In dry falls, like the one Wisconsin experienced in 2024, you can help trees go into winter healthy by continuing to provide water to them until the leaves start falling (for deciduous trees) or until the ground starts freezing (for conifers).

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White Masses On Alder Are Woolly Aphids

Posted on by akabelowsky
Photo showing a group of woolly alder aphids on an alder branch.

A group of woolly alder aphids on an alder branch. / Photo Credit: Linda Williams, Wisconsin DNR

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

Have you seen white lumps of fluff on alder stems? Woolly alder aphids congregate together for the winter. These aphids produce white filaments from their bodies to protect them from predators. When they congregate, they can look like a big clump of snow stuck to alder branches.

Continue reading “White Masses On Alder Are Woolly Aphids” →

Forest Health Staff To Join Oak Disease Webinar

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A screen grab of a webpage on the United States Environmental Protection Agency website discussing a pest management webinar set for Dec. 10, 2024.

The U.S. Environmental Protection Agency will present an international webinar titled “Deadly Oak Diseases” from 1 to 2:30 p.m. Tuesday, Dec. 10. / Graphic Credit: U.S. Environmental Protection Agency

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

The U.S. Environmental Protection Agency (EPA) will present an international webinar titled “Deadly Oak Diseases” from 1 to 2:30 p.m. (CST) Tuesday, Dec. 10.

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Forest Health Staff Public Appearance Set

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Wisconsin Department of Natural Resources Forest Health team leader Becky Gray will discuss invasives during a presentation to the Southeastern Wisconsin Invasive Species Consortium, set for Wednesday, Nov. 6, at Havenwoods State Forest in Milwaukee. / Photo Credit: Art Kabelowsky, Wisconsin DNR

Forest Health team leader Becky Gray has planned an appearance at a public meeting of the Southeastern Wisconsin Invasive Species Consortium (SEWISC). She’ll give a presentation covering invasives on a statewide level.

The event will take place from 1 to 4 p.m. Wednesday, Nov. 6, at Havenwoods State Forest, 6141 N. Hopkins St., Milwaukee, WI. More information is available on the SEWISC website.

Check Conifers For Invasive Adelgids

Posted on by akabelowsky
Photo showing white, cottony hemlock woolly adelgid egg sacs on a hemlock branch.

White, cottony hemlock woolly adelgid egg sacs on a hemlock branch. / Photo Credit: Bill McNee, Wisconsin DNR

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

Hemlock woolly adelgid (HWA) and balsam woolly adelgid (BWA) are invasive, aphid-like insects that cause tree mortality in North America. Neither has been found in Wisconsin so far, but they are likely to arrive at some point, as they have been confirmed in Michigan.

HWA (Adelges tsugae) is an invasive, sucking insect pest of hemlock trees. The white, cottony egg sacs of HWA can be seen on the undersides of hemlock branches at the base of needles year-round. HWA saliva enters the tree while feeding. The saliva is toxic and causes needle drop and twig dieback, progressing to tree mortality in 4-10 years.

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A Busy Summer For Urban Forestry Interns

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By Dan Buckler, DNR Urban Forest Assessment Specialist; daniel.buckler@wisconsin.gov or (608) 445-4578

Every year, the summer ends faster than one could pronounce Liquidambar styraciflua, and this year was no exception. Hopefully, while you are trying to recall proper Latin pronunciations, your summer is still filled with enjoyable, productive or illuminating activities. That was certainly the case for the DNR Urban Forestry summer internship program. This summer, staff worked with Southern University students Taylor Colman and Priscilla Loh on a variety of different data collection projects, filling the internship’s eight weeks with species identification, tree mensuration and tree health assessments. Continue reading “A Busy Summer For Urban Forestry Interns” →

Spruce Budworm Defoliation Continues

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

Closeup photo showing that webbing created by the spruce budworm caterpillar holds needles and frass and protects the caterpillar. A pupa hangs from the branch.

Webbing created by the spruce budworm caterpillar holds needles and frass and protects the caterpillar. A pupa hangs from the branch. / Photo Credit: Linda Williams, Wisconsin DNR

Although symptoms weren’t as prevalent as in 2023, this year marked yet another year of defoliation from spruce budworm.

Another severe year of defoliation causes additional stress on the trees. Even though there has been a lot of rainfall this spring, it’s still stressful for the trees to face repeated years of defoliation by spruce budworm before they begin to decline and die.

Continue reading “Spruce Budworm Defoliation Continues” →