Pest

Trapping project found no non-native beetles

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

The Wisconsin DNR’s forest health team received funding to trap for non-native beetles in 2018. This project was funded by the US Forest Service through an Early Detection and Rapid Response (EDRR) grant. The project is complete, and we happily share that we did not find any non-native beetles!

Forest health staff member Scott Schumacher is hanging a Lindgren funnel trap (12 funnels stacked to look like a tree trunk) from a tree branch to survey for non-native beetles.

Forest health staff member Scott Schumacher hangs a Lindgren funnel trap to survey for non-native beetles.

The Forest Service periodically provides funding to states to trap for non-native bark and ambrosia beetles. The goal of trapping is to detect, delimit and monitor newly introduced exotic beetles and to quickly assess and respond to newly detected infestations.

We placed traps at 12 high-risk sites in Jefferson, Waukesha, Milwaukee, Racine, Manitowoc, and Brown counties. Sites were selected in collaboration with the Wisconsin Department of Agriculture, Trade and Consumer Protection and were based on proximity to large commercial port entries on Lake Michigan or recycling facilities for pallets and other waste packaging. Three Lindgren funnel traps (12 funnels stacked to look like a tree trunk) and lures were assembled at each site and checked every two weeks between early May and early August. Specimens collected from the traps were sent to a Forest Service taxonomist for identification.

New northern oak wilt detections

By Paul Cigan, forest health specialist, Hayward. Paul.Cigan@wisconsin.gov; 715-416-4920 and Linda Williams forest health specialist, Woodruff. Linda.Williams@wisconsin.gov; 920-360-0665

Oak wilt (OW) was confirmed for the first time in Bayfield and Douglas counties and in 16 new northern townships in 2018. The new OW infections occurred on a range of properties, including county, tribal, private, U.S. Forest Service and Board of Commissioners of Public Lands. Wisconsin Department of Natural Resources (DNR) forest health staff are working proactively with affected property managers and landowners to address these infections and prioritize disease prevention and detection in the future.

 

Oak wilt distribution map. Confirmed counties are displayed in red. Confirmed townships are displayed in pink 6-mile square blocks.

The greatest risk of overland transmission in northern Wisconsin is from April 15 to July 15, when fungal spores readily infect open wounds. Most of these new cases occurred during this time frame due to stem and branch damage. The primary causes of damage were roadside brush clearing, pruning, lot clearing and storm-caused branch breakage. Fungal spores may have come from diseased oak firewood and unprocessed wood recently transported into these areas.

Image shows a group of oak trees. Northern red oak on far left is in wilting stage of disease (leaves on but wilting and dropping). Oak on far right has mechanical root collar injury. Dairyland Township, Douglas County.

OW disease center. Oak on far left was infected through belowground root contact with tree damaged in lot clearing (far right). Dairyland Township, Douglas County (photo taken by Paul Cigan).

If oak wilt is present in or within 6 miles of the county where you manage oak, your management activities may be affected by seasonal harvesting restrictions to reduce OW introduction and impact. Read DNR’s oak harvesting guidelines for more information and refer to the list below of new 6 square mile blocks by township and county to see if OW has been detected near your property.

Bayfield County
Barnes T45N R9W
Cable T43N R7W
Drummond T45N R8W
Douglas County
Dairyland T43N R15W
Gordon T44N R11W
Langlade County
Elcho T34N R11E
Langlade T33N R13E
Neva T32N R11E
Sawyer County
Couderay T39N R8W
Hayward T41N R8W
Hunter T40N R7W
Round Lake T41N R8W
Spider Lake T42N R7W
Vilas County
Boulder Junction T42N R6E
Lac du Flambeau T41N R5E, T40N R5E
St. Germain T40N R8E

Please report any suspected oak wilt infections to your local DNR forester or regional forest health specialist and learn more about oak wilt identification and biology on the DNR oak wilt webpage. To learn more about firewood rules and how you can help reduce transmission of pests and diseases, including oak wilt, visit the DNR firewood page.

10 oak leaves lain on downed log display bronze discoloration typical of oak wilt. Midrib and base of leaf are still green.

Bronzed leaves fallen from infected oak. Leaves were observed beneath infected northern red oak. Cable Township, Bayfield County (photo taken by Paul Cigan).

ALB: What to watch for in Wisconsin

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

We do NOT have Asian longhorned beetle (ALB) in Wisconsin at this time, but it’s good to be on the lookout for it. Every year folks submit reports of insects that they suspect to be ALB, but to date they have always been confirmed as the native whitespotted sawyer (sometimes called pine sawyer), which attacks stressed conifers rather than the maple and other hardwood species preferred by ALB. If you find a beetle that you suspect to be ALB, please collect the beetle, take some pictures, and send them to your forest health specialist, or to the University of Wisconsin Insect Diagnostic Lab for identification.

Asian longhorned beetle is a large beetle. They are smooth and shiny black with white spots and blotches on their wing covers. Photo by Joe Boggs, Ohio State University, bugwood.org

Asian longhorned beetle is a large beetle. They are smooth and shiny black with white spots and blotches on their wing covers. Photo by Joe Boggs, Ohio State University, bugwood.org.

 

Our native pine sawyer beetle appears dusty or pitted, but is often mistaken for Asian longhorned beetle. Photo by Linda Williams.

Our native pine sawyer beetle appears dusty or pitted, but is often mistaken for Asian longhorned beetle. Photo by Linda Williams.

ALB can be a very destructive pest. It is typically introduced, unintentionally, to new areas via wooden pallets, wood packing materials, or firewood. The Don’t Move Firewood website has some great tips for safe transport of firewood, how to find firewood locally, as well as a list of other invasive insects and diseases to be aware of when buying or using firewood.

USDA APHIS, which conducts eradication efforts wherever ALB is found, recently announced that an area of Ohio was officially ALB-free, and the quarantine was subsequently removed. Earlier this year in March, a separate area of Ohio was also declared ALB-free. That leaves just one area of Ohio with ALB quarantines still in effect. Eradication of ALB can take decades to complete and involves extensive efforts including tree removal and chemical treatments. States with current ALB quarantines include: Massachusetts, New York and Ohio.

For more info on ALB, check out the USDA APHIS ALB webpage, and as always, please let us know if you think you have come across a forest health concern, including ALB.

Invasive stink bug numbers increasing

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

Invasive brown marmorated stink bugs (BMSB) are now well established and reproducing in southern and central Wisconsin. This fall we are getting our first reports of large numbers of BMSB gathering on the sides of houses looking for places to overwinter. This problem will continue to get worse as stink bug populations increase and their range expands. Damage to important crops, ornamental plants and trees will also be a major concern. BMSB is known to feed on a wide variety of plants including apples, tomatoes, corn, soybeans, silver maple and walnut.

Adult brown marmorated stink bugs are ½ to ¾ inch long, brown with alternating white and black patches on the edge of the abdomen and white bands on the antennae and have smooth shoulders that lack spines.

An adult brown marmorated stink bug. Photo by P.J. Liesch, University of Wisconsin Insect Diagnostic Lab.

Researchers are working on ways to manage the pesky bugs. One new method being explored is hanging black netting soaked in insecticide at locations where the bugs congregate, such as doors on the north and east sides of structures.

Samurai wasps are another promising lead. These stink bug-killing wasps found their way into the U.S. on their own over the past few years, but researchers are also working with lab-reared samurai wasps that they hope to release. Samurai wasps parasitize the eggs of BMSB but do not sting humans or other animals.

For more information about identification and management check out:
University of Wisconsin-Extension
WisContext
Midwest Stink Bug app

Return of Asian multicolored ladybugs

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

Multicolored Asian ladybeetles, true to their name, come in a range of colors, from orange to red, with a variety of spot sizes and numbers.

Multicolored Asian ladybeetles, true to their name, come in a range of colors, from orange to red, with a variety of spot sizes and numbers. Photo: Linda Williams

Multicolored Asian ladybeetles are not native to Wisconsin. Although there are numerous native ladybugs in the state, only the Asian variety are known to aggregate in buildings in the fall and become nuisances. Continue reading “Return of Asian multicolored ladybugs”

Pine root collar weevil

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

This jack pine is leaning due to damage at its base from pine root collar weevil. Photo: Linda Williams

This jack pine is leaning due to damage at its base from pine root collar weevil. Photo: Linda Williams

Damage from pine root collar weevils was recently reported in Lincoln, Marinette, and Vilas counties on jack pine trees. Pine root collar weevils are known to attack and kill all types of pines, although scotch, red, and jack pine are the most common hosts in Wisconsin. The insects attack pine trees of varying sizes – from large saplings to those of small pole size. Adult weevils deposit eggs at the tree’s base; larvae then bore under bark and feed in the root collar area, effectively girdling the tree. Soil and bark near the root collar becomes blackened and soaked with pitch. Feeding larvae are visible in tunnels under the bark. Continue reading “Pine root collar weevil”

Emerald ash borer detected in Kewaunee County

Communities known to have emerald ash borer as of September 2018 are shown in green, with Kewaunee County highlighted in red. Modified from a map by the Wisconsin Dept. of Agriculture, Trade and Consumer Protection (DATCP).

Communities known to have emerald ash borer as of September 2018 are shown in green, with Kewaunee County highlighted in red. Modified from a map by the Wisconsin Dept. of Agriculture, Trade and Consumer Protection (DATCP).

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

In August, two separate infestations of emerald ash borer (EAB) were found in rural areas of Kewaunee County. EAB has spread through Wisconsin over the last few years, so these detections were expected. The first infestation spans the towns of Carlton and Franklin in the southern part of the county. A county resident reported the second infestation, located in the Town of Casco, in late August. The pest is likely present in other parts of the county as well.

Public comment period for EAB silviculture guidelines revision closes October 9

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

Ash trees dying from an EAB infestation. Photo: Troy Kimoto, Bugwood.org

Ash trees dying from an EAB infestation. Photo: Troy Kimoto, Bugwood.org

The Wisconsin DNR is seeking public comments on a proposed revision to silviculture guidelines for emerald ash borer (EAB). Stand-level EAB silviculture guidelines were originally released in 2007, with periodic reviews and updates. A DNR technical team and stakeholder advisory committee prepared the current version using multiple sources of information, including recent research findings, identification and locations of new EAB infestations, economic considerations, and experience gained from implementing previous versions of the guidelines.

The draft document and information about the public comment process can be found at  https://dnr.wi.gov/news/input/Guidance.html#open through Tuesday, October 9, 2018. All comments must be submitted by that date.

Look for gypsy moth egg masses

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

Gypsy moth egg masses. Photo: Bill McNee

Fall is an excellent time to look for and dispose of gypsy moth egg masses produced by adult moths this summer. Gypsy moth egg masses are felt-like, tan-colored patches about the size of a nickel or quarter that gypsy moth females deposit in protected places. Surveying for egg masses helps property owners predict how high populations of the insect will be during the subsequent spring and summer. Since egg masses usually don’t hatch until April, information gained from fall/winter surveys can be used to mitigate gypsy moth damage before the following season.  Continue reading “Look for gypsy moth egg masses”

Brown branch tips on jack pine

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

After brushing away sawdust, exit/entrance holes, as tiny as the beetles themselves, become visible. A beetle is inside, peeking out. The marks at the bottom of the photo depict millimeters.

After brushing away sawdust, exit/entrance holes, as tiny as the beetles themselves, become visible. A beetle is inside, peeking out. The marks at the bottom of the photo depict millimeters.

Jack pine tip beetle (Conopthorus banksianae) is a tiny bark beetle that bores into the twig tips of pines. Damage from jack pine tip beetle was observed this summer on jack pine trees in Marinette, Vilas, and Lincoln counties and on white pine in Waupaca County. These beetles attack and kill the outer 4-6 inches of twigs, leaving hollow piths. The piths can be diagnostic in determining whether an insect or disease killed the branch tip. The damage, which may appear significant since the dead needles remain on the branch tip and there can be many dead branch tips on a single tree, is rarely severe enough to be detrimental to the tree; no control is recommended.

Jack pine tip beetles kill the outer few inches of twigs. The two yellow circles show where sawdust was pushed out of the twig by adult beetles. Photos: Linda Williams

Jack pine tip beetles kill the outer few inches of twigs. The two yellow circles show where sawdust was pushed out of the twig by adult beetles. Photos: Linda Williams