White spotted sawyer

Our native pine sawyer has a “spot” between the elytra (yellow arrow) that Asian longhorned beetle does not have. They also will appear dusty or pitted.

Our native pine sawyer has a “spot” between the elytra (yellow arrow) that Asian longhorned beetle does not have. They also will appear dusty or pitted.

White spotted sawyer, sometimes called Pine Sawyer, is a native longhorn beetle. It is often mistaken for Asian Longhorned Beetle (ALB). How can you tell the difference between our native beetle and ALB?  First of all, size: ALB is a big burly beetle, while our native sawyer beetle looks slim in comparison. Second, ALB has a very smooth shiny appearance with distinct white spots on black wing covers, whereas our native sawyer beetle will appear pitted or dusty, and the white spots may be less distinct or absent. Finally, our native beetle will have a nice white dot “between its shoulders” where the wing covers meet, and ALB does not have this. 

Adult pine sawyer beetles feed on the bark of twigs which can cause branch tip mortality.

Adult pine sawyer beetles feed on the bark of twigs which can cause branch tip mortality.

Pine sawyer larvae develop in weakened, recently dead, or recently harvested conifers. Larvae first feed in the phloem layer then progress to inner wood. They will pupate within the tree and adults will chew their way out leaving large round exit holes. Adults feed on needles and the bark of twigs. Areas this year which will attract white spotted sawyers include areas of storm damaged pine, and areas of conifer decline due to high water levels, as well as any other areas where conifers are stressed. 

If you find a beetle and are unsure whether it’s ALB or our native sawyer, please take some photos to send for identification. 

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

Poplar vagabond aphid

Poplar vagabond aphid feeding on the buds of aspen or cottonwood cause the tree to form a fleshy, hollow gall around the insects.

Poplar vagabond aphid feeding on the buds of aspen or cottonwood cause the tree to form a fleshy, hollow gall around the insects.

Galls caused by poplar vagabond aphid form at the ends of aspen and cottonwood branches. The galls are caused by aphids feeding at the tips of twigs. This feeding causes the tree to grow an elaborate structure that the aphids can live inside. One of the galls in the photo is broken open so you can see the aphids inside. This damage does not usually kill the tree, but reduces branch growth because the formation kills the terminal buds. The aphids feed during the spring and early summer within the gall, and then leave to feed on an unknown second host plant. When the aphids leave the gall it will turn brown and woody, and will remain on the tree for several years before weathering off. Adult aphids return later in the fall and lay eggs on the woody gall or in crevices in the bark. Eggs will hatch the following spring and repeat the process. For control, prune the galls prior to egg hatch early in the spring. Because the aphids return to the same trees with the original galls it is common to see a single tree heavily infested while a nearby tree will have no galls at all. I have always seen this problem in trees that are open grown, either along the edge of a stand, along a roadway or fence row, or in a yard. I’m not sure how much of a problem it is in the interior of a stand.

Poplar vagabond aphids, which are covered in a white waxy material, are protected inside the large hollow galls formed by the tree. They suck the trees’ sap.

Poplar vagabond aphids, which are covered in a white waxy material, are protected inside the large hollow galls formed by the tree. They suck the trees’ sap.

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

Oak leaf tier and oak leaf roller

Oak leaf rollers and oak leaf tiers fold over or roll leaves which protect them from predators.

Oak leaf rollers and oak leaf tiers fold over or roll leaves which protect them from predators.

Last month I reported on a location in Marinette where oak leaf tier and oak leaf roller were defoliating oak. Since then I had a report of this same combination of pests causing defoliation near Rhinelander. Typically this defoliation is not severe, but when the leaves are rolled up or folded in half it can make it look like the defoliation is more severe.

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

Of historical interest, 25 years ago (1992) and 50 years ago (1967)

25 years ago – 1992

  • Frost – On June 20, the temperature dropped to 25°F in many locations throughout Wisconsin. This caused injury to several tree species including: black ash, balsam fir, red pine, northern pin oak, and spruce in northwestern Wisconsin, and red pine and northern pin oak in Oneida and Vilas counties, north-central Wisconsin. Severe damage to new shoots of white spruce and balsam fir Christmas trees occurred in Taylor, Langlade, Oneida, Lincoln and Oconto counties. Injury to hardwoods often caused defoliation. Conifers affected by the frost had curled and crooked shoots that eventually died. In Vilas County, most of the injured red pine and oak did not reflush. In Eau Claire County, western Wisconsin, spruce, black walnut and several species of pine were injured. Seedling and sapling-size red pine were injured in Clark and Chippewa counties. Balsam fir, white spruce and white pine Christmas trees in northern Wisconsin were also injured by the early summer frost. Severe loss of new growth.
  • White Grubs – Phyllophaga In Marinette County, (Section 16, T30N, R20E) high numbers of white grub larvae were observed in plantings of ash, maple, oak and walnut. These trees were being planted in alfalfa. In Portage county, (NWNW, Section 4, T21N, R7E) all larval stages were present at the time of planting red pine in sod on a 13 acre area. In Washburn County, heavy mortality occurred in a red pine planting due to white grub feeding. Heavy numbers of grubs were reported in new tree plantations in Door, Kewaunee and Manitowoc counties. The adult stage of white grubs, the May and June beetles, were observed in large numbers at night in urban areas in Oconto, Marinette and Marathon counties. Progeny of these beetles could produce heavy damage to nearby young tree plantings in the next two years.

50 years ago – 1967

  • Pissodes approximatus Damage by this weevil was associated with red pine plantings on poor sites or frost pockets in the Northeast Area. The most severe infestations were found in Marinette, Oneida and Vilas counties during surveys for Scleroderris lagerbergii (Gremman).
  • White-Pine Weevil, Pissodes strobi (Peck). Populations were generally low in all areas of the state. About 10% of the leaders were infested in a small white pine planting in Washburn County (Section 8, T41N, Rl3W). A few terminals of Norway spruce and Scotch pine Christmas trees were infested in Langlade and Oconto county plantations, and survival of weevils was poor in the east central counties. Heaviest infestations were reported from the West Central Area where 20% to 30% of the current leaders were infested in a few white pine plantations and averaged 10% to 15%.  Although no white pine weevil control projects were conducted in the West Central Area this year, additional insecticide test plots were established on Black River State Forest plantations. Further investigation of a reported white pine weevil attack on red pine in Trempealeau County reported in 1966 (p. 7, Annual Report 1966) appears more likely to have been the work of Pissodes approximatus Hopkins. Large numbers of these weevils were found on stumps of red pine, cut for Christmas in the fall of 1966, when the site was re-examined in the spring of 1967. Older stumps showed evidence of previous attacks typical of P. approximatus.  Evaluation of evidence available indicated that terminal attacks in 1966 occurred because breeding P. approximatus populations exceeded available stump areas and overflowed to the stems and terminals of living trees.

Content taken from the Forest Pest Conditions for Wisconsin Annual Reports from 1967 and 1992.

Gypsy moth adults appearing now

Female gypsy moth lays an egg mass.

Female gypsy moth lays an egg mass.

As of mid-July, DNR forest health staff have received reports of adult gypsy moths present as far north as Burnett County. The brown-shelled pupae and white female moths can be crushed with a stick. The remaining caterpillars will also pupate soon, and where the caterpillars are a problem, they can be crushed, drowned in soapy water, or sprayed with insecticide or insecticidal soap. Continue reading “Gypsy moth adults appearing now”

Emerald ash borer new finds in Wisconsin

EAB emergence map as of July 10, 2017. Tan colors in the north are approaching peak emergence, light green is peak emergence, and olive is past peak emergence.

EAB emergence map as of July 10, 2017. Tan colors in the north are approaching peak emergence, light green is peak emergence, and olive is past peak emergence.

Much of Wisconsin has reached peak emergence of emerald ash borer adults.

EAB continues to be found in new areas. Wisconsin tracks EAB at the municipality or township level. Quarantine counties are shown in tan and infested areas are shown in green on the EAB Detections and Quarantine map below.

New county quarantines

  • none

New finds in counties already quarantined

  • Crawford County – city of Prairie de Chein
  • Grant/Iowa County — city of Muscoda
  • Milwaukee County — village of Whitefish Bay
  • Outagamie County — town of Grand Chute
  • Sauk County – village of West Baraboo
  • Waukesha County — village of Merton
EAB quarantine map. Counties shaded in tan are quarantined for EAB, and include much of the southern half of Wisconsin, as well as other counties. Areas shaded in green are the townships and municipalities where EAB has actually been identified, and show that not all counties that are quarantined are fully infested.

EAB quarantine map. Counties shaded in tan are quarantined for EAB, green areas are townships and municipalities where EAB has actually been identified.

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

Defoliation by rose chafers and Japanese beetles is showing up.

Rose chafers and Japanese beetles are starting to cause problems in some areas this summer. So far reports and damage are generally light for Japanese beetles, but in some areas rose chafer defoliation is noticeable. 

Rose chafers are beetles that can defoliate many plant species. They have fairly long legs, and are a dusty mustard color.

Rose chafers are beetles that can defoliate many plant species. They have fairly long legs, and are a dusty mustard color.

Rose chafer defoliation was reported from Florence, Marinette, Oconto, Vilas, and Waupaca counties this year. Rose chafers are more common in areas with sandy soil where they will lay their eggs. The eggs hatch into white grubs which live in the soil and feed on grass and weed roots. My books inform me that birds can die if they eat adult rose chafers because of a poison in the beetles that affects the heart of small, warm-blooded animals. For information on rose chafer control, check out UW Extension publication A3122.

The last significant defoliation that I noted from rose chafer was in 2012, and before that it was 2005. These beetles feed on a wide variety of plants and prefer blossoms, but they will skeletonize leaves as well. Control is difficult because the adults are good fliers and can easily fly in from neighboring areas to re-infest your freshly sprayed plants. 

Japanese beetle populations will emerge in southern Wisconsin first, typically by the first part of July. Some areas of the state have building populations while others, like the Madison area, may have populations that exploded in the past and are more stable now. These insects are occasionally mistaken for EAB because they have some metallic green coloring near their heads.  More commonly people will refer to the multicolored Asian ladybeetles as Japanese beetles, but the ladybugs are ladybugs and Japanese beetles are scarab beetles.

Japanese beetle adults feed on the flowers and leaves of over 300 plant species, including trees, shrubs, and herbaceous plants. They can cause significant defoliation. The larval stage of Japanese beetle is a white grub that lives in the soil and feeds on plant roots.  University of Wisconsin Extension has a Japanese beetle webpage including information on the damage caused by the adults, the damage caused by the white grubs, and control measures that are useful on the adults and the larvae. 

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

Spruce budworm defoliation is present

Spruce budworm defoliation is not as noticeable this year, although it is still present as you can see here with many needles missing.

Spruce budworm defoliation is not as noticeable this year, although it is still present as you can see here with many needles missing.

Spruce budworm damage is present this year but in many areas it is less noticeable than in past years. I believe this is due to a couple of things:

  1. The many storms we had this spring with heavy rainfall and strong winds may have washed some of the caterpillars out of the trees. They definitely washed budworm damaged needles off the tree. Damaged needles typically remain on the tree and turn a rusty brown, so not having these needles on the tree makes it less obvious where defoliation is present this year.
  2. Due to the constant rainfall this year, the growth on balsam fir and spruce seems to be quite good in general, which leads to additional green needles on the tree this year. This makes the trees look more green and less defoliated, but spruce budworm is still there.

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

Black canker and willow scab on willow

Black canker causes twig mortality and a sunken area on the branch. Photo by Mike Schuessler.

Black canker causes twig mortality and a sunken area on the branch. Photo by Mike Schuessler.

Do you have willow that is looking thin and sad this year?  In addition to some frost damage earlier this year, I’ve checked out several areas where black canker and willow scab are causing defoliation and fine branch mortality.  I’ve noticed this in Brown, Door, Kewaunee, Marinette, Oconto, and Waupaca counties.

Early in my career with the department I recall checking out a willow planting in Manitowoc County that had a lot of black canker killing the fine branches, but since then I haven’t run into it much.  Black canker starts by infecting a leaf but quickly moves into the petiole and into the twig where it causes a small sunken canker. This can cause the twig tip to wilt, shrivel, and die. Willow scab will also cause the twig tips to wilt, shrivel, and die. Willow scab and black canker can often be found affecting the same tree and are more common in years when we have a cool wet spring. 

New growth impacted by willow scab and black canker will shrivel and die.

New growth impacted by willow scab and black canker will shrivel and die.

Repeated defoliation of a tree due to black canker or willow scab can significantly impact growth and form because many branch tips will be killed. More information and pictures are available online by Cornell on black canker and willow scab

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

Woolly alder aphids on maple

Woolly alder aphids secrete waxy filaments or fine hairs to protect themselves from predators. They live part of the year on maple and part of the year on alder.

Woolly alder aphids secrete waxy filaments or fine hairs to protect themselves from predators. They live part of the year on maple and part of the year on alder.

Maple trees with white fluffy, stringy things on their leaves and twigs have woolly alder aphid (Paraprociphilus tessellatus). Populations seem rather high this year. This aphid species requires both alder and maple to complete its life cycle, spending spring and summer on maple and the remainder of the year on alder. While on alder they are a plump, bluish colored aphid covered by white, waxy filaments. They will often be found in a group, forming a solid mass of white fluff on the stems. 

When present on maple they are sometimes referred to as maple blight aphid. They don’t usually do any significant damage to either maple or alder but they can be quite noticeable at times because of the large patches of fluff when they congregate in an area.  High populations of these aphids on maple can create enough honeydew (aphid excretions) to create a sticky layer on any objects underneath the maples. Sooty mold can then grow on the sticky layer, so it is recommended to wash off things under these trees on a regular basis. I’ve seen or had reports of woolly alder aphids on maple from Door, Langlade, Oconto, and Oneida counties.

Woolly alder aphids often congregate in large white masses on alder where they will overwinter.

Woolly alder aphids often congregate in large white masses on alder where they will overwinter.

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.