Care for your woods

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.

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Forest Health Team Offers Seven New Fact Sheets, Updates Website

Posted on by akabelowsky
A preview of the new Wisconsin Department of Natural Resources Forest Health fact sheet on spongy moth.

A preview of the new Wisconsin Department of Natural Resources Forest Health fact sheet on spongy moth. Graphic Credit: Wisconsin DNR

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

The Wisconsin Department of Natural Resources’ (DNR) Forest Health team has debuted seven new fact sheets, providing information on various forest insects and diseases as well as tips on how to deal with their emergence on your property.

The new fact sheets provide details on spongy moth, oak wilt management, spruce budworm, jack pine budworm, tamarack insects (larch casebearer and eastern larch beetle), red pine pocket decline and mortality and a comparison of common spring defoliator caterpillars (forest tent caterpillar, eastern tent caterpillar and spongy moth).

Additionally, the Forest Health team has updated and/or refreshed the look of its 13 existing fact sheets.

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Upcoming Environmental Justice Webinars

Posted on by patricialindquist

The Arbor Day Foundation and the Chicago Region Trees Initiative are each hosting an environmental justice webinar next week.

On Tuesday, July 18, from 11 a.m. – noon, the Arbor Day Foundation is presenting Environmental Justice in Tree Cities: Where to Begin? A conversation with Dr. Christine Carmichael of Fair Forests Consulting for the Tree City USA network. In this webinar, attendees will learn the defining characteristics of environmental justice, evidence of environmental injustices in urban and community forestry, and strategies to integrate environmental justice principles into their Tree City USA programs.

If you, your organization, your city or town are new to environmental justice concepts and practices, this webinar will equip you with tangible next steps to advance your efforts, including ways to measure your success and adapt as needed along the way. 

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Acorn Pip Galls, Woolly Catkin Galls All The Same

Posted on by akabelowsky

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

Photo of acorns showing small pip galls.

Pip galls are small, tongue-like protrusions emerging from under the caps of acorns. / Photo Credit: Linda Williams, Wisconsin DNR.

Gall wasp life cycles can be complex. Did you know that acorn pip galls, which I’ve written about several times, have another part of their life cycle that is entirely different? This stage is called the woolly catkin gall.

Both woolly catkin galls and acorn pip galls are caused by Callirhytis quercusoperator, a species of cynipid gall wasp. This gall wasp takes two years to complete development by going through the two parts of its life cycle. Both parts of the life cycle are completed on northern red oak in our area.

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High Beech Scale Moving Beyond Door County

Posted on by akabelowsky

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

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

Photos of white 'wool' coating on trees with beech scale.

Examples of white “wool” coating on trees heavily infested with beech scale at Kohler-Andrae State Park (left) and in the Town of Beecher in Marinette County (right). / Photo Credit: Bill McNee (left) and Linda Williams (right), Wisconsin DNR.

Fourteen years after first detecting beech scale (Cryptococcus fagisuga, a non-native insect) in Door County, sites with high populations of beech scale have been found in additional counties. Beech scale is believed to have spread through the range of American beech in Wisconsin’s eastern counties, but until now has only been seen at low levels outside of Door County.

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White Pine Weevil Damage And Management Options

Posted on by akabelowsky

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

Photo of a white pine tree showing weevil damage.

A dead terminal leader, resulting from an attack by white pine weevil. Photo: Linda Williams, Wisconsin DNR.

White pine weevil (Pissodes strobi) is a native insect that can kill the terminal leader of white pine, jack pine and spruce. Wisconsinites often refer to this insect as Tip Weevil.

The insects prefer to attack stout terminal leaders. When the terminal leader dies, lateral branches grow upward and compete to take over apical dominance. This can leave a noticeable crook for decades. If two or more lateral branches take over, forking can occur. New terminal leaders may be attacked in subsequent years, causing more crook or forking.

Spruce and jack pine tend to recover better from weevil damage than white pine because the lateral branch that takes over apical dominance often creates a less prominent crook.

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Is it Invasive Giant Hogweed?

Posted on by akabelowsky

Erika Segerson-Mueller, DNR Forest Health invasive plants program specialist, Oshkosh
Erika.SegersonMueller@wisconsin.gov or 715-492-0391

Photo of umbel of a giant hogweed plant.

Umbel of a giant hogweed plant. This invasive plant can grow stems 2-4 inches in diameter and can grow as tall as 15 feet. Photo: USDA APHIS PPQ, Oxford, North Carolina; Bugwood.org

This time of year, calls start rolling in about potential sightings of the invasive plant giant hogweed (Heracleum mantegazzianum). Although occurrences of the plant remain rare in Wisconsin, from late May through early July giant hogweed is often confused with a native plant, cow parsnip (Heracleum maximum).

Both are large plants with similar habitat preferences. They prefer shady areas and are often found along stream banks, roadsides and ditches. Giant hogweed is a prohibited species under Wisconsin’s Invasive Species Rule NR40. Its fast growth rate crowds out native vegetation and erodes soil, and skin contact can potentially cause irritation.

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Eastern Tent Caterpillar Webs Common

Posted on by akabelowsky

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

Photo of web of eastern tent caterpillars.

Eastern tent caterpillars and their webs start out small but grow quickly. Photo: Linda Williams, Wisconsin DNR.

Have you seen trees along roadsides with white webs in them? Eastern tent caterpillars (ETC) are hatching and beginning to feed on host trees, including cherry, apple and crabapple.

Landowners and homeowners may notice the white silken tents forming in branch forks. Although they form unsightly nests, ETC is a native insect, so management is not typically necessary. Even completely defoliated trees will produce new leaves within a few weeks.

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Diseases Take Aim At Spongy Moth

Posted on by akabelowsky
Photo of tree showing caterpillars killed by virus and fungus

Caterpillars killed by nucleopolyhedrosis virus (NPV) hang in an inverted “V” orientation; caterpillars killed by the fungus Entomophaga maimaiga hang vertically. Photo: Wisconsin DNR.

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

With this spring’s dry weather in Wisconsin came predictions of the largest spongy moth population in years.

When spongy moth populations are high, we often see heavy mortality of the larger caterpillars due to two pathogens. Heavy caterpillar mortality will reduce the severity of the following year’s outbreak and often causes a population crash during the current year. If a heavy die-off of caterpillars is observed, please let your local DNR Forest Health Specialist know about it.

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Spongy Moth Focus Of Video, Webcast

Posted on by akabelowsky

Art Kabelowsky, DNR Forest Health outreach and communications specialist
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

Add “YouTube Influencer” to the long list of career accomplishments of Andrea Diss-Torrance, Ph.D.

With the spongy moth caterpillar population on the rise in many areas of Wisconsin this season, the Wisconsin Department of Natural Resources stepped into action last month.

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