Emerald Ash Borer
Surveys

Visual Survey Methods

Visual detection surveys for emerald ash borer are conducted from the ground. Surveyors determine if trees are infested by visually scanning them for emerald ash borer-like symptoms and signs. Symptoms characteristic, but not definitive, of emerald ash borer include branch dieback, epicormic sprouting at the base or along the trunk, woodpecker feeding, and bark cracks. Emerald ash borer signs include metallic green adult beetles, cream colored larvae under the bark, D-shaped emergence holes in the bark and S-shaped larval feeding tunnels under the bark. For a complete description and images of what to look for please see emerald ash borer signs and symptoms.

Detection Tree Survey Methods

A detection tree is an ash tree (preferably declining in health) that the surveyor girdles, or wounds, causing the tree to release beetle-attracting chemicals. The tree is typically girdled at waist height and an 18-inch sticky band is placed above the wound. The sticky band, which is used to catch adult beetles, is checked biweekly June through August. Girdled trees are left to stand for one or two growing seasons before they are felled in fall or winter and their bark is removed. Bark removal allows surveyors to detect emerald ash borer larvae and their S-shaped galleries. The larvae are found in the phloem region, sandwiched between the inner bark and outer sapwood. Tree peeling is an essential part of the survey because research has shown that detection trees may be infested with emerald ash borer even if no adult beetles are collected on the sticky band. Additionally, research has found that detection trees are the best tool available for detecting low-density emerald ash borer infestations.

2004 Survey Summary

We conducted surveys during summer 2004 (June-September), the focus of which was to (1) collect baseline data on the current health status of Wisconsin's ash resource, and (2) detect emerald ash borer infestations in Wisconsin. Visual and detection tree surveys were conducted in 51 state parks and forests, with emphasis on ash trees in campgrounds and firewood storage and sale areas. We focused on state parks and forests because emerald ash borer will most likely move into Wisconsin via larvae-infested wood (firewood, unprocessed logs, and nursery stock). Of the 4189 trees surveyed, 83.8 percent showed no emerald ash borer symptoms. The remaining 16.2 percent exhibited emerald ash borer-like symptoms, such as crown dieback or epicormic sprouting, but emerald ash borer larvae and adults were not were positively identified on any trees. Overall, the survey showed the ash resource in Wisconsin is healthy and no emerald ash borer infestations were detected.

Identified Agrilus species collected during 2004 detection tree surveys. Emerald ash borer was not collected and is for comparison only.

2005 Survey Summary

Visual survey

During summer 2005 we continued to look for emerald ash borer by conducting both visual and detection tree surveys. Visual surveys targeted the ash resource in Wisconsin's private and county campgrounds (northeastern and southeastern WI), while detection tree surveys focused on floodplain forests along the Lower Wisconsin River Way (LWRW). We targeted these areas because the risk of emerald ash borer infestation increases in areas where non-local firewood is frequently brought in and burned.

Our visual detection surveys of 2447 trees in 101 campgrounds did not find any emerald ash borer infestations. Campgrounds were located throughout Dane, Door, Forest, Green, Jefferson, Langlade, Marinette, Oconto, Oneida, Rock, Vilas, Walworth and Waukesha counties. The overall health status of ash trees in these private and county campgrounds is good: An estimated 96 percent of surveyed trees appeared healthy. We observed no serious outbreaks of other ash pests or diseases. These results parallel those of the 2004 emerald ash borer visual survey.

Detection tree survey

Similarly, no emerald ash borer infestations were found by detection tree surveys. A total of 14 detection trees were monitored along a 23-mile stretch of the LWRW, between Mazomanie Beach in Dane County and Long Island in Richland County. No emerald ash borer adults were found on the sticky bands and no larvae were seen under the bark. However, numerous long-horned beetles (Cerambycidae) were collected, with the two most common being the redheaded ash borer (Neoclytus acuminatus) and banded ash borer (Neoclytus caprea). Also collected were numerous native, metallic wood-boring beetles (Buprestidae), including a species of Chrysobothris, and four species of Agrilus (none were emerald ash borer).

In addition to surveys conducted by the Department of Natural Resources, the University of Wisconsin-Extension conducted visual surveys in urban areas throughout Milwaukee, Racine and Kenosha counties. Detection tree surveys were also conducted in the Chequamegon-Nicolet National Forest by the U.S. Forest Service. Emerald ash borer was not detected during these surveys.

2006 Survey Summary

In 2006 the DNR completed its third year of surveying for emerald ash borer. In an effort to detect the emerald ash borer before the infestation becomes widespread in Wisconsin, the DNR continued to conduct both detection tree and visual surveys throughout the state.

Visual Surveys

Visual surveys were conducted at 235 private and county campgrounds and recreational areas throughout central, south central and southwestern Wisconsin. More than 24,000 campsites were visited, and more than 3500 ash trees were surveyed.

Visual surveys resulted in finding no emerald ash borers. The overall health of the ash trees surveyed was good, with 96.4% showing no signs or symptoms of EAB. Approximately one third of the ash trees surveyed exhibited epicormic sprouting and less than six percent exhibited yellow leaves, branch dieback, wood-pecker feeding, bark cracks or were dead (see chart). However, there were 18 suspect trees detected, which were noted for follow-up in 2007. Follow-up surveys are deemed necessary when any combination of three or more emerald ash borer-like symptoms (branch dieback, epicormic sprouting, woodpecker feeding, yellow foliage, bark cracks) are present.

Various commonly encountered insect pests and pathogens of ash were also detected, in addition to environmental stressors and mechanical wounding. The most frequently observed ash health issue was the foliar disease anthracnose, found on just over one third of the trees surveyed (see graph). The remaining pests, pathogens and environmental stressors were less frequently encountered and found on less than 20% of the trees surveyed. Additionally, more serious health issues such as ash yellows and drought stress were observed, but were few.

Detection Tree Surveys

Unidentified Buprestidae larvae found during peeling.

Seven detection trees previously established on state forest properties along the Lower Wisconsin Riverway (LWRW) in 2005 were felled and peeled during 2006. Research suggests that allowing detection trees to stand through two growing seasons, versus a single one, may prove more attractive to emerald ash borer. The detection trees lined a 23-mile stretch of the LWRW between Mazomanie Beach in Dane County and Long Island in Richland County. In November, detection trees were felled and the bark peeled to look for developing emerald ash borer larvae and their associated serpentine galleries in the cambium layer. No emerald ash borer larvae were detected during bark peeling. However, other larvae identified during the bark peeling included one undetermined species of metallic wood-borer (not emerald ash borer), and a species of long-horned beetle. In addition, ash bark beetle and ash cambium miner galleries were evident in the cambium layer and red-headed ash borer galleries were detected in the sapwood.

WI DNR also contracted with scientists from Michigan Tech University to set detection trees on state property. One hundred thirty-one detection trees were established on 21 state park properties. These trees were visited throughout the summer and examined for the presence of adults. Fifty-three of the detection trees were felled and peeled in the fall in order to look for developing larvae. The remainder of the detection trees were scheduled to be felled in 2007. Detection trees previously established on these state forest properties in 2004 and 2005 were also felled and peeled during 2006. No emerald ash borer larvae were found.

2007 Survey Summary

Visual Surveys

Figure 1: Map of 2007 EAB visual and detection tree survey locations conducted in WI. Blue squares represent detection tree locations (5-7 trees established per location) and green circles represent visual survey locations.

Figure 2: Emerald ash borer detection tree, complete with girdle and sticky band.

Visual surveys were conducted in private and county campgrounds in 2007 (Figure 1). Private and county campground lands were the target survey area due to their increased risk for emerald ash borer introduction through firewood transportation. Currently, only state lands are monitoring the origin of incoming firewood and have constituted a permanent ruling requiring that all firewood originate from within a 50-mile radius of the camper’s destination and from within the state of Wisconsin. View more information on the firewood ruling or the numerous pests that firewood transports.

Survey sites and results

Visual surveys were conducted in 80 private and county campgrounds throughout southeastern Wisconsin and in Marinette County. Over 5600 campsites were surveyed, resulting in the evaluation of 2650 ash trees for the presence of the emerald ash borer or other ash pests and diseases. Characteristic symptoms of an emerald ash borer infestation include epicormic sprouting, branch dieback and woodpecker feeding. Characteristic signs include D-shaped exit holes, serpentine galleries located just beneath the bark and the presence of emerald ash borer larvae or adults. Our visual survey efforts detected no emerald ash borer infestations in the private and county campgrounds surveyed.

However, other commonly encountered, but non-threatening ash insect pests and diseases were detected during the surveys. Insect pests observed included the ash bark beetle, the clearwing moth, and the redheaded ash borer. Diagnosis was determined by exit hole evaluation. Foliar and bud insects such as the ash flower gall mite, ashleaf gall mite and ash plant bug were observed as well. Diseases observed included anthracnose on the foliage and ash yellows brooms on the main stem. The anthracnose was widespread across all survey sites, but just a handful of trees exhibited the brooming associated with ash yellows.

Detection Tree Surveys

Upon completion of four years of visual survey work looking for the emerald ash borer in state parks and private campgrounds, the pest was not detected in Wisconsin. However, scientific research has determined that visual survey methods are not effective at detecting emerald ash borer infestations unless the insect population is at a very high density. Additionally, scientific research recommends the use of detection tree surveys for detection of low-density emerald ash borer infestations. In 2007, WI DNR extended its contract with Michigan Technological University for a second year pertaining to the establishment, monitoring and peeling of ash detection trees in Wisconsin’s state parks and recreation areas. Private campgrounds did not have any detection trees established.

Survey sites and results

A total of 141 detection trees were established in 26 state park and recreation areas during May 2007 (Figure 1). Each of the 26 sites had 2-4 previously established detection trees in place from the 2006 detection tree survey, resulting in a total of 5-7 detection trees at each site. Detection trees consist of a girdle around the main stem at waist height and the placement of an 18-inch-wide sticky band just above the girdle (Figure 2). The sticky band is used to catch emerald ash borer adults during their flight season. Sticky bands were inspected for emerald ash borer adults biweekly, June through August. During the fall, after the adult flight season had ended, detection trees are felled and peeled in search of emerald ash borer larvae and galleries. During the fall of 2007, a minimum of four trees per property were cut and peeled. Trees selected were a combination of those girdled in 2006 and 2007. The remaining 2-3 trees per site were left standing for a second year to be felled and peeled during fall 2008. No emerald ash borer life stages were found during detection tree surveys in 2007.

EAB Purple Panel Trap

Purple panel traps were used as a survey tool in Wisconsin for the first time in 2007. To date, researchers still consider the use of detection trees to be the best method for detecting low-density emerald ash borer infestations; however, there are situations in which panel traps may be favored over detection trees in order to prevent the loss of the tree. Such situations include surveying in areas where the tree may be considered a prize urban or campground shade tree or when surveying where the ash resource is limited, but risk still exists (e.g. firewood piles, mills and nurseries).

Figure 3: Emerald ash borer purple panel trap. Photo by Joe Francese

Figure 4: Properly hung EAB purple panel trap in an open grown ash tree. Photo provided by Bruce Slagoski

Trap description

Emerald ash borer panel traps are made of a purple corrugated plastic board (Figure 3). Traps are triangular with an open center. Each panel of the trap measures 14 X 24 inches and is coated with glue on its exterior. Trap hanging is recommended on an open grown or edge ash tree at a height of 33-40 feet above ground (Figure 4). Research suggests that the emerald ash borer is visually attracted to the color of purple used for the traps.

Trap locations

Purple panel traps were hung in 17 locations across central and southern Wisconsin (Figure 5). Trap locations included nine state parks and forests (Governor Dodge, High Cliff, Interstate, Kettle Moraine – North, Mirror Lake, Peninsula, Peshtigo River, Richard Bong Recreational Area and Rocky Arbor), two Dane County parks (Riley Depee and Fish Camp) and seven municipalities (Beloit, Fitchburg, Madison, Monroe, Oak Creek, Sheboygan and Stevens Point). Two traps were hung at each location early June through late August. After trap removal, traps were checked for emerald ash borer adults.

Trap catch summary

No emerald ash borer adults were detected on purple panel traps. Other insects of interest that were collected include four other species of metallic wood-boring beetles (Figure 6) and another commonly encountered ash pest, the redheaded ash borer.

Additionally, Figure 7 depicts a summary of all emerald ash borer visual and detection tree survey efforts conducted by Wisconsin DNR 2004 – 2007.

Figure 5: EAB purple panel trap locations.

Figure 6: Four species of metallic wood-boring beetles were collected from the purple panel traps. Identification is in process.

Figure 7: Map depicting WI DNR EAB survey efforts 2004 – 2007. Blue squares represent detection tree locations (2-11 trees established per location) and green circles represent visual survey locations.