Pest

Severe Spruce Budworm Defoliation Hits In Northwest

Posted on by akabelowsky

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

Photo taken through magnifying lens of spruce budworm caterpillars.

Spruce budworm overwinters as tiny caterpillars (yellow arrow) that migrate to the buds before they start to swell in the spring. A magnifying lens is needed to see them at this stage. / Photo Credit: Linda Williams, Wisconsin DNR.

For the 11th consecutive year in Wisconsin, spruce budworm has caused significant defoliation on spruce, balsam fir and tamarack in some areas of the state.

This year, areas with widespread severe defoliation include Oneida and Vilas counties, with Forest, Iron, and Langlade counties also showing significant defoliation.

Continue reading “Severe Spruce Budworm Defoliation Hits In Northwest” →

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.

Continue reading “High Beech Scale Moving Beyond Door County” →

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.

Continue reading “White Pine Weevil Damage And Management Options” →

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.

Continue reading “Diseases Take Aim At Spongy Moth” →

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.

Continue reading “Spongy Moth Focus Of Video, Webcast” →

ATCP 21 Rule Changes Coming

Posted on by akabelowsky

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

Photo of an adult emerald ash borer.

The statewide quarantine for emerald ash borer will end July 1, as one of several permanent rule changes proposed by the Wisconsin Department of Agriculture, Trade and Consumer Protection.

Changes are coming to some of Wisconsin’s rules for plant inspection and plant control, following legislative approval of a proposal from the Department of Agriculture, Trade and Consumer Protection (DATCP).

The rule changes for ATCP 21 (Clearinghouse Rule CR 22-022), in the works since 2020, will go into effect on July 1.

One of the permanent rule changes involves the end of the state quarantine for emerald ash borer. Other quarantines to be rescinded are those for pine shoot beetle and thousand cankers disease of walnut trees.

The changes were recommended by DATCP for one or more of the following reasons: a lack of serious pest impacts, the quarantine outliving its ability to contain the pest, and/or federal deregulation.

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Multiple Oak Defoliators Active Now

Posted on by akabelowsky
Photo of oak leafroller caterpillar on a leaf.

Oak leafroller caterpillars web leaves together as they feed. Photo: Wisconsin DNR.

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

Watch for defoliators in your oak trees this summer. You may have already heard news reports about spongy moth caterpillar populations being high this year, but there are some native caterpillars to watch for this year as well.

In 2022, oak leafroller caterpillars caused significant defoliation to oaks in areas of northeastern and northwestern Wisconsin, as well as in Blue Mound State Park. Many other areas experienced lesser amounts of defoliation from oak leafroller.

Continue reading “Multiple Oak Defoliators Active Now” →

Prepare — Spongy Moth Caterpillars To Return

Posted on by akabelowsky

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

Spongy moth caterpillars clustered below a sticky barrier.

Spongy moth caterpillars clustered below a sticky barrier. Photo: Mark Guthmiller, Wisconsin DNR

This June and July, spongy moth populations are predicted to reach damaging levels in parts of Wisconsin. Populations began to rise in 2020, and this is likely to be the third year of the pest outbreak in some regions of southern Wisconsin.

At present, damaging populations are expected to be most noticeable in southern counties, counties to the north of the city of Green Bay, and in far northern Wisconsin near Lake Superior. Additional areas are likely to have high populations that are more concentrated in size.

Continue reading “Prepare — Spongy Moth Caterpillars To Return” →

Report Tree-Of-Heaven To Help Monitor For Spotted Lanternfly

Posted on by patricialindquist

By Anne Pearce, Invasive Plants Association of Wisconsin

Spotted lanternfly is on its way to Wisconsin

Tree-of-heaven showing leaves and fruits. Photo: Chuck Bargeron, University of Georgia, Bugwood.org

Spotted lanternfly (Lycorma delicatula) is an invasive insect that threatens a variety of plant species, mostly woody plants. It has not yet been found in Wisconsin, but it is steadily moving toward us from the eastern United States. Both juvenile (nymphs) and adult spotted lanternfly feed by sucking sap from the stem, branches, twigs and leaves of host plants. This weakens the plant and can contribute to the plant’s death. Because spotted lanternfly impacts a wide variety of agricultural crops (like grapes and hops), nursery crops (like roses), and hardwood trees (like maple, walnut, willow, and poplar), it is a high priority pest in Wisconsin.

Continue reading “Report Tree-Of-Heaven To Help Monitor For Spotted Lanternfly” →

First Recovery of Emerald Ash Borer Enemy Made

Posted on by akabelowsky

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

Map showing Spathius Galinae recovery in Manitowoc County

Sites where EAB biological controls have been recovered as of March 2023. The Spathius galinae recovery site is indicated by a red star. Blue dots show Tetrastichus planipennisi recovery sites. Municipal EAB detections are in green. Map: Wisconsin DNR

Two adult wasps, collected last December as pupae from an emerald ash borer (EAB) gallery at Kiel Marsh State Wildlife Area in Manitowoc County, have recently been identified as Spathius galinae.

This find marks the first time that S. galinae has been recovered in Wisconsin, confirming that the adult wasps released at this site over the last few years were able to attack EAB larvae and reproduce successfully. The “EAB wasps” were released as biological controls to help reduce EAB populations over the long term.

This wasp species has a longer ovipositor than the other EAB larval parasitoid currently released in Wisconsin (Tetrastichus planipennisi), allowing S. galinae to attack EAB larvae that are beneath thicker bark.

Spathius galinae was first released in Wisconsin in 2016, and approximately 1,000 of this species were released at Kiel Marsh in 2019 and 2020. Recovery surveys are conducted several years after initial releases, giving the wasps time to reproduce and spread. Continue reading “First Recovery of Emerald Ash Borer Enemy Made” →