Pests

Look For Spongy Moth Egg Masses And Take Action

Posted on by akabelowsky
Closeup of a person scraping spongy moth egg masses into a cup.

A putty knife, plastic knife or similar object can be used to gently scrape spongy moth egg masses into a cup of soapy water. The water can be discarded after two days. / Photo Credit: Wisconsin DNR

By Bill McNee, DNR Forest Health Specialist, Oshkosh
Bill.McNee@wisconsin.gov

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.

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Watch For Squirrel, Porcupine Damage In Spring

Posted on by akabelowsky
Closeup of small squirrel tooth marks on a tree's mainstem.

Squirrel tooth marks are small and look like narrow scratches from which the animals have removed the tree’s bark. / Photo Credit: Wisconsin DNR

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

As winter transitions into spring, you may notice patches of tree bark that have been removed. But what did the damage?

Several animals, including squirrels and porcupines, can chew or strip bark from trees. This can occur on hardwoods and conifers, older trees and young saplings. Damage can be enough to kill branches or even the entire tree.

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Upcoming Trainings

Posted on by janness

* These training opportunities are provided as an information service only and do not constitute an endorsement from the Wisconsin Department of Natural Resources (DNR).

See below for information on training topics and events, including tree diseases and treatments, pest management, landscaping, career advancement, invasive species, pruning, volunteer management, new research, partnerships and developing an urban forest management plan. Continue reading “Upcoming Trainings” →

Increased Tree Mortality Seen As Spongy Moth Outbreak Ends

Posted on by akabelowsky
Mature spongy moth larva on a tree at Potawatomi State Park in Door County, July 2025.

Mature spongy moth larva on a tree at Potawatomi State Park in Door County, July 2025. / Photo Credit: Wisconsin DNR

By Bill McNee, DNR Forest Health Specialist, Oshkosh
Bill.McNee@wisconsin.gov  

Wisconsin’s recent period of high spongy moth populations (an “outbreak”) came to an end in 2025, as the remaining known hotspots were aerially sprayed or naturally collapsed. Only a handful of large larvae were observed or reported by property owners.

Spongy moth populations are likely to be low across the state for at least the next few years. However, it is possible that some sites may experience a population increase before then, if local weather conditions are favorable for the insect.

Continue reading “Increased Tree Mortality Seen As Spongy Moth Outbreak Ends” →

Report Invasive Hemlock Insects This Winter

Posted on by akabelowsky
Small, white hemlock woolly adelgid eggs found on the needles of a tree in Bastian, Virginia, in 2017.

Small, white hemlock woolly adelgid eggs are found on the needles of a tree in Bastian, Virginia, in 2017. / Photo Credit: Bill McNee, Wisconsin DNR

By Mike Hillstrom, Forest Invasive Pest Coordinator, Fitchburg
Michael.Hilstrom@wisconsin.gov or 608-513-7690

Hemlock woolly adelgid (HWA) looms as a major threat to Wisconsin’s hemlock trees. As the infestation of these invasive, aphid-like insects spreads in Michigan and other states in the eastern United States, Wisconsin is preparing to respond when it arrives.

HWA is most evident in winter and spring as fluffy, white, woolly balls that are present at the base of hemlock needles. These fluffy, waxy balls cover adult female adelgids and eggs.

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Did You Know? Facts About Pine Webworm

Posted on by akabelowsky

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

Webbing and a collection of frass (caterpillar excrement) around these cones is the web nest of pine webworm. / Photo Credit: Wisconsin DNR

Pine webworm (Pococera robustella) is a native moth whose caterpillars feed on pine needles. In Wisconsin, the caterpillars prefer young jack pine and red pine. A single generation per year occurs in Wisconsin.

Young larvae mine needles, feeding within the needle. Older larvae form a compact web that they fill with small, oval pieces of frass. In early fall, the larvae drop to the ground to pupate and spend the winter.

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Keep It Local When Stocking Up On Firewood For Winter

Posted on by akabelowsky
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

Posted on by akabelowsky
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

Posted on by akabelowsky
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

Posted on by akabelowsky
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.

Continue reading “Fall Webworm Spins Its Way To Attention” →