Pests

Forest Health Team Debuts Two New Fact Sheets

Posted on July 6, 2026July 4, 2026 by akabelowsky

An image of the front page of a DNR fact sheet.

The front page of the Wisconsin DNR’s new Forest Health Fact Sheet on oak decline. / Graphic Credit: Wisconsin DNR

By Art Kabelowsky, DNR Outreach and Communications, Fitchburg
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

The Wisconsin Department of Natural Resources Forest Health team has published two new fact sheets, bringing the total count of its fact sheet offerings to 26.

The new fact sheets:

Fall Webworm: DNR Publication FR-622u discusses basic information on the biology of the insect (Hyphantria cunea), its life cycle, potential lookalike caterpillars and management options.
Oak Decline: DNR Publication FR-622v covers the tricky topic of oak decline, which is not caused by one distinct forest pest or problem but instead is the result of multiple factors — some predisposing, some inciting and some contributing — that work in combination to cause decline.

The fact sheets are designed in full color, with photos, and are meant to be printed out for reference or to carry into the field. They can also be viewed online. They can be printed on standard letter-sized paper. Most fact sheets are two pages, meant for two-sided printing; a few are four-page documents.

A complete directory of links to all DNR Forest Health fact sheets is available online.

Watch for Asian Longhorned Beetle

Posted on July 6, 2026July 4, 2026 by akabelowsky

Closeup of an insect crawling on a person's hand.

An adult Asian longhorned beetle. / Photo Credit: Wisconsin DNR

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

Asian longhorned beetle (ALB) has not been found in Wisconsin, but early detection is critical to eliminating it from infested areas. Forest Health workers from Wisconsin, Michigan, Minnesota and Manitoba, Canada, recently had the opportunity to visit an active ALB infestation in South Carolina to learn how to identify infested trees. This experience will greatly enhance staff’s ability to detect ALB and respond rapidly.

Continue reading “Watch for Asian Longhorned Beetle” →

Watch For Spongy Moth Caterpillars And Tree Damage This Summer

Posted on June 10, 2026June 19, 2026 by akabelowsky

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

Close-up of caterpillar feeding on a leaf.

A spongy moth caterpillar feeds on a leaf. / Photo Credit: Wisconsin DNR

Property owners are encouraged to monitor their trees for spongy moth larvae and damage this summer to determine whether control measures are needed.

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.

Continue reading “Watch For Spongy Moth Caterpillars And Tree Damage This Summer” →

Spruce Budworm Outbreak Continues In 2026

Posted on June 10, 2026 by akabelowsky

Young spruce budworm larvae begin feeding as buds break, causing the new growth to crook where feeding damage occurs. Webbing shown in the photo is also common. / Photo Credit: Wisconsin DNR

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

The spruce budworm outbreak is continuing for yet another year in some areas of northern Wisconsin.

Continue reading “Spruce Budworm Outbreak Continues In 2026” →

Forest Tent Caterpillar Outlook

Posted on June 10, 2026June 10, 2026 by akabelowsky

Forest tent caterpillar larvae displaying gregarious, clustering behavior on a tree stem. / Photo Credit: Wisconsin DNR

By Paul Cigan, DNR Forest Health Specialist, Hayward
dnr.wisconsin.gov/topic/foresthealth/staff, 715-416-4920

Populations of forest tent caterpillar (FTC) are likely to remain low throughout northern Wisconsin this growing season, continuing a record 23-year statewide trend.

Spring egg mass surveys showed a low presence of overwintering egg masses, suggesting that any defoliation this season is likely to be localized. Overwintering egg masses present on the twigs of deciduous twigs and branch tips are counted during surveys to forecast FTC population density and the associated risk of heavy defoliation going into spring leaf-out.

Continue reading “Forest Tent Caterpillar Outlook” →

Forest Health Staffers Plan Appearances

Posted on June 10, 2026 by akabelowsky

A worker in the woods, holding a young tree to be planted.

Wisconsin DNR Forest Insect Pest Specialist Mike Hillstrom gives a presentation during a New Forester Training session in Marinette County in 2024. / Photo Credit: Bill McNee, Wisconsin DNR

By Art Kabelowsky, DNR Outreach and Communications, Fitchburg Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

Mike Hillstrom, the Wisconsin Department of Natural Resources Invasive Forest Pest Coordinator, will give a public presentation on forest invasive species from 10 a.m. to noon Saturday, June 20, at Lake Kegonsa State Park in Stoughton.

The talk will be part of the informational and educational events sponsored as part of the DNR’s Invasive Species Awareness Weekend.

Continue reading “Forest Health Staffers Plan Appearances” →

Upcoming Training

Posted on March 17, 2026March 18, 2026 by janness

Photo Credit: Wisconsin DNR

* 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 training on urban forestry basics, tree risk fundamentals in Spanish, plant diseases and pests, invasive species, student apprenticeships, nut trees and other urban forestry resources. Continue reading “Upcoming Training” →

Look For Spongy Moth Egg Masses And Take Action

Posted on March 2, 2026March 18, 2026 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.

Continue reading “Look For Spongy Moth Egg Masses And Take Action” →

Watch For Squirrel, Porcupine Damage In Spring

Posted on March 2, 2026March 18, 2026 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.

Continue reading “Watch For Squirrel, Porcupine Damage In Spring” →

Upcoming Trainings

Posted on January 26, 2026January 26, 2026 by janness