Month: July 2022

20 Year Anniversary Of Emerald Ash Borer Confirmation In North America

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

Five metallic green beetles against a white background.

Early photo of EAB adults taken in June 2002, prior to the insect species being identified. Photo: USDA Animal and Plant Health Inspection Service

The beginning of July marked 20 years since we received news of an unidentified beetle that turned out to be the emerald ash borer (EAB), one of North America’s greatest tree killers. On July 1, 2002, DNR forest health staff received an email from USDA Animal and Plant Health Inspection Service about this beetle being associated with declining ash in southeast Michigan:

This is to notify you that in the past few days we have responded to a report of an insect pest feeding on ash in the western suburbs of Detroit. This follows what has been a series of reports of declining ash in this area over the past couple of years. However, in the past we have not been able to associate it with any particular insect or disease. We are now seeing a boring insect emerging from the infested trees in various sites… The adult, which is emerging now, resembles the shape and size of two lined chestnut borer. It is emerald, metallic green in color and leaves a D-shaped exit hole, similar to bronze birch borer… Continue reading “20 Year Anniversary Of Emerald Ash Borer Confirmation In North America”

Leafroller Charged With Severe Oak Defoliation

By Paul Cigan, DNR Forest Health Specialist, Hayward, Paul.Cigan@wisconsin.gov or 715-416-4920; Mike Hillstrom, DNR Forest Health Specialist, Fitchburg, Michael.Hillstrom@wisconsin.gov or 608-513-7690; and Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov or 920-360-0665

Oak leafrollers feed on leaves and roll/fold them with strands of silk. Photo: Wisconsin DNR

An outbreak of oak leafroller moth, Archips semiferanus, has been observed in many parts of Wisconsin this year. Oak leafrollers are native, early-season defoliators. This year they have consumed and rolled up oak leaves, giving the tree crowns a thin, yellow appearance. Continue reading “Leafroller Charged With Severe Oak Defoliation”

Lecanium Scale: A Sticky Situation

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

Lecanium scale is popping up in a few areas of Oneida and Vilas counties. These scale insects insert their mouthparts into twigs and suck the sap of the tree. They release honeydew, which can be collected by ants or may coat leaves and anything located under infested trees (i.e., yard furniture or vehicles). Sooty mold can grow on that sticky material and turn things black, so homeowners may want to rinse off the honeydew from outdoor items on a regular basis.

Brown lumps on a twig.

The brown lumps on this stem are lecanium scales. Photo: Wisconsin DNR

Continue reading “Lecanium Scale: A Sticky Situation”

Another Year Of Spruce Budworm Defoliation

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

Spruce budworm is a native insect with periodic outbreaks that defoliate spruce and balsam fir in the Midwest. While these caterpillars have pupated and moths are already emerging to mate and lay eggs, spruce budworm defoliation is now becoming noticeable in northern and central Wisconsin as clipped needles stuck in caterpillar webbing turn rusty red.

Dark colored spruce budworm caterpillar feeding on new balsam fir foliage.

Spruce budworm larvae had webbed together the new growth. Note some clipped needles in the webbing that will turn rusty red in color. Photo: Wisconsin DNR

Continue reading “Another Year Of Spruce Budworm Defoliation”

Spiny Oak Sawfly And Red Oak: A One-Sided Love Story

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

The spiny oak sawfly feasts again. While defoliation by this insect is common in understory oaks, this year, lower branches of overstory oaks have also seen damage. All damage so far has been observed on red oaks. Previously we saw a widespread outbreak in 2005 with lesser reports of damage in 2007, 2016, 2017 and 2021.

A small caterpillar on the underside of an oak leaf.

Spiny oak sawfly larvae. Photo: Wisconsin DNR

Continue reading “Spiny Oak Sawfly And Red Oak: A One-Sided Love Story”