Insect

Spruce budworm and balsam fir mortality in northern Wisconsin

Posted on by margueriterapp

By Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665 

Spruce budworm defoliation was severe in many areas of northern Wisconsin this year. New needles on balsam fir and spruce were eaten, although in most areas the balsam fir had greater amounts of defoliation than the spruce. Feeding by this native caterpillar for several years in a row can cause trees to start to decline and even die, which is occurring in a number of areas of northern Wisconsin.

Mortality of balsam fir due to repeated defoliation by spruce budworm. Green trees in this photo, including hardwoods and pines, are not fed upon by spruce budworm.

Mortality of balsam fir due to repeated defoliation by spruce budworm. Green trees in this photo, including hardwoods and pines, are not fed upon by spruce budworm.

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Redheaded pine sawfly reported in northern Wisconsin

Posted on by margueriterapp

By Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665 

For the second year in a row, colonies of redheaded pine sawfly have been reported on understory red pine in northern Wisconsin, with the most reports coming from Vilas County. Redheaded pine sawfly was also noted in Portage County in central Wisconsin this year.

Redheaded pine sawfly larvae feed as a group, as shown in this photo where many sawflies are clustered on a single twig.

Redheaded pine sawfly larvae feed as a group.

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August is Tree Check Month!

Posted on by patricialindquist

Donald Duerr, USDA Forest Service, Bugwood.org

The USDA is encouraging everyone to spend 10 minutes checking their trees for the Asian longhorned beetle (ALB). August is an ideal time to spot this devastating pest as it emerges from trees.

Although ALB has not been discovered in Wisconsin, it is crucial that we keep an eye out for it. The quicker any infestations are discovered and reported, the easier it will be to eradicate. Three states currently have regulations in place for ALB: Massachusetts, New York, and Ohio.

ALB attacks a wide variety of trees including maple, elm, ash, birch, poplar, and willow. Signs of infestation include dime-sized exit holes, shallow scars in bark, sawdust-like material on the ground or tree branches, dead branches, and the beetle itself. Note that the Asian longhorned beetle is sometimes confused with the white-spotted pine sawyer, a native longhorned beetle.

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Wondering about large yellow wasps?

Posted on by margueriterapp

If you’ve noticed large yellow wasps flying around this summer, you may be wondering whether you’ve seen the Asian giant hornet (aka “murder hornet”). This probably gave you some pause considering all the headlines they received earlier this year,  but fortunately for Wisconsin and much of the Midwest, murder hornets have not yet been found in the region.

Close-up photo of cicada killer.

The cicada killer is a common native insect in the Midwest.

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Revised aerial spray guide now available

Posted on by margueriterapp

By Bill McNee, forest health specialist, Oshkosh, Bill.Mcnee@wisconsin.gov, 920-360-0942

Increasing reports of gypsy moth, forest tent caterpillar and other defoliators this summer may indicate rising populations and increased defoliation over the next few years. A recently revised guide to aerial sprays for landowners is now available.Cover page of the updated aerial spray guide. Continue reading “Revised aerial spray guide now available” →

Fall webworm activity in July

Posted on by margueriterapp

By Todd Lanigan, forest health specialist, Eau Claire, Todd.Lanigan@wisconsin.gov, 715-210-0150

Fall webworm started showing up in early July. This native insect feeds on deciduous trees and shrubs and appears every year in yards and forests. It is often noticed first by the loose webbing over branch tips. It can even completely cover a small tree with webbing. If you look inside the webbing, you will find partially eaten leaves, frass (caterpillar poop) and both live and dead caterpillars.

Fall webworm caterpillars atop

Fall webworm larvae feed within webbed enclosures at branch tips. Credit: Courtney Celley, US Fish & Wildlife Service.

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Forest tent caterpillar populations high in small localized areas

Posted on by margueriterapp

Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665

Forest tent caterpillar (FTC) is a native insect with periodic outbreaks. Reports of high populations have been coming in this spring from the towns of Nokomis, Three Lakes and Sugar Camp in Oneida County. There is some defoliation in these areas, but the geographic extent of damage is still limited. When looking for caterpillars in northeastern Wisconsin, it was not difficult to find at least one or two of them, which is an increase from past years when it was difficult to find any caterpillars at all.

Close-up photo of forest tent caterpillar shows the insect's unique "footprint" design that runs along the top of its back.

Forest tent caterpillars go through several instars, or growth stages. Colors vary between stages but all have the cream-colored “boot prints” down their backs.

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Basswood leaves defoliated and trees looking thin

Posted on by margueriterapp

Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665 

Basswood trees in Forest, Marinette and Oconto counties are looking very poor this year. The leaves are damaged, misshapen or completely missing. Several things seem to be happening, but the worst offenders seem to be a late frost/freeze and a suspected infestation by introduced basswood thrips.

Evidence of basswood thrips on a single leaf; some defoliation and dieback.

Evidence of suspected basswood thrips infestation in early spring.

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Updated emerald ash borer silviculture guidelines now available

Posted on by margueriterapp

By Bill McNee, forest health specialist, Oshkosh, bill.mcnee@wisconsin.gov, 920-360-0942

The Division of Forestry has completed a revision of the emerald ash borer silviculture guidelines to help foresters prepare for and respond to the arrival of emerald ash borer (EAB) in a forest stand.

Cover page of new guidelines. Continue reading “Updated emerald ash borer silviculture guidelines now available” →

New insect and disease factsheets available

Posted on by margueriterapp

By Mike Hillstrom, forest health specialist, Fitchburg, Michael.Hillstrom@wisconsin.gov, 608-513-7690

The forest health team has produced four new factsheets since the start of 2020. These resources are designed to be informative, 2-page documents for a wide audience that includes landowners, foresters and natural resource professionals, educators, and more. The new factsheets of 2020 are linked below, and more will be announced as they are finalized:

Please check them out and our other recently updated factsheets about Heterobasidion root disease, oak wilt, conifer bark beetles, and hickory decline and mortality. You can find all of these and more forest health publications in the publications catalogue and on the DNR forest health webpage.