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Privacy and Disclaimer Notice
1 May 2000
U.S. DEPARTMENT OF INTERIOR
1.0. INTRODUCTION: PURPOSE AND NEED FOR ACTION....................1
1.1. Proposed Action..............................................1
1.2. Background Information and Need for Action...................2
1.2.1 Eastern Hemlock Forests
1.2.2 HWA and Decline of Eastern Hemlock Forests
1.2.3 Importance of Hemlock Forests at DWGNRA
1.2.4 The Threat of HWA at DWGNRA
1.2.5 The Additional Threat of Hemlock Borer Beetle
at DWGNRA
1.3. Opportunity for Action.......................................6
1.4. Decisions to be Made.........................................7
1.5. Scope of this Environmental Assessment.......................7
1.5.1 Related NEPA Documents
1.5.2 Scoping Activities and Issues
1.5.3 Issues Considered in Detail
2.0. ALTERNATIVES, INCLUDING THE PROPOSED ACTION..................9
2.1. Alternatives Considered, but Dismissed.......................9
2.1.1 Ground spraying with horticultural oils or
insecticidal soaps
2.1.2 Aerial spraying
2.1.3 Systemic insecticides
2.1.4 Pheromone traps, or other methods of disrupting
reproduction
2.1.5 Release of a biological control other than
P. tsugae beetles
2.2. Alternatives Considered in Detail.........................10
2.2.1 Alternative 1: No Action
2.2.2 Alternative 2: Release P. tsugae beetles
(Proposed Action)
3.0 ENVIRONMENTAL CONSEQUENCES OF THE ALTERNATIVES................13
3.1 Issue 1: Possible Human Nuisance of P. tsugae Beetles.........13
3.1.1 Alternative 1: No Action
3.1.2 Alternative 2: Release P. tsugae beetles
3.2 Issue 2: Possible Non-target Effects of P. tsugae Beetles.....13
3.2.2 Alternative 2: Release P. tsugae beetles
3.3 Issue 3: Questionable Effectiveness of P. tsugae Beetles......15
3.3.1 Alternative 1: No Action
3.3.2 Alternative 2: Release P. tsugae beetles
3.4 Issue 4: Continued Decline of Hemlock Forests.................16
3.4.1 Alternative 1: No Action
3.4.2 Alternative 2: Release P. tsugae beetles
3.5 Cumulative Effects........................................18
4.0 LIST OF AGENCIES AND PERSONS CONSULTED........................18
4.1 National Park Service.....................................19
4.2 Other Natural Resource Professionals......................19
4.3 External Scientists.......................................19
5.0 REFERENCES....................................................20
FIGURES
Figure 1:
HWA survey sites and P. tsugae beetle release sites
Figure 2:
1999 hemlock tree conditions and HWA infestations
at permanent plots
1.0 INTRODUCTION: PURPOSE AND NEED FOR ACTION 1.1 Proposed Action
The National Park Service proposes to release laboratory-reared, predatory "Japanese lady beetles" (Pseudoscymnus tsugae) in hemlock forests at Delaware Water Gap National Recreation Area. The goal of the proposed action is to prevent, as soon as possible and to the greatest extent possible, the decline of hemlock forests in the recreation area resulting from infestations of an exotic (non-native) insect, the hemlock woolly adelgid (Adelges tsugae). Achieving this goal would prevent the loss of important ecological, aesthetic, and recreational resources associated with these forests.
The proposed action is consistent with laws and policies guiding natural resource management in the National Park Service (NPS). First, it is consistent with the legislated responsibility of the NPS "to conserve the scenery and the natural and historic objects and the wild life therein and...leave them unimpaired for the enjoyment of future generations" (1916 NPS Organic Act). Second, it is consistent with the law establishing Delaware Water Gap National Recreation Area (DWGNRA), which includes specific provisions for "public outdoor recreation benefits" and "preservation of the scenic, scientific, and historic features contributing to public enjoyment" of the recreation area (Public Law 89-158, section 5, 1965). Finally, it is consistent with NPS policies guiding the use of biological controls as part of Integrated Pest Management and exotic species management: "Biological control (biocontrol) may be a long-term solution to controlling some exotic species" (NPS-77 1991).
Releases of Japanese lady beetles during May or June, 2000 are proposed for two sites, one in New Jersey and one in Pennsylvania. The New Jersey release site would be the hemlock forest surrounding VanCampens Brook, between Millbrook Village and "Blue Mountain Lakes Road" in northwest Warren County and southwest Sussex County. The Pennsylvania release site would be the hemlock forest surrounding Adams Creek, between U.S. Route 209 and State Route 2001 in Pike County (Figure 1). The New Jersey Department of Agriculture's Beneficial Insect Laboratory would provide and release Japanese lady-beetles (hereafter simply called "beetles") at the New Jersey site, and the U.S. Department of Agriculture (USDA) Forest Service would provide and release beetles at the Pennsylvania site. Approximately 10,000 beetles would be released at each site (depending on beetle availability).
The NPS would coordinate with the USDA Forest Service and follow established protocols to monitor and evaluate the beetle releases for at least three consecutive years following release. Monitoring would be conducted to determine the survival, establishment, and dispersal of the beetle populations, and the effectiveness of the beetles in reducing hemlock woolly adelgid (HWA) populations and protecting hemlock tree health at a forest stand level. The NPS would prepare annual reports, summarizing results from the previous year(s), by June of 2001, 2002, and 2003. In addition, the NPS would complete surveys within the park for three species of insects: (1) the hemlock angle moth (Semiothisa fissinotata), (2) the woolly alder aphid (Prociphilus tesselatus), and (3) the harvester butterfly (Feniseca tarquinius).
1.2 Background Information and Need for Action
1.2.1 Eastern Hemlock Forests Eastern hemlock is the Official State Tree of Pennsylvania, and has been called "the redwood of the east." It is an evergreen conifer that is widely distributed in the United States from eastern Minnesota to Maine, and south to Alabama along the Appalachian Mountains. The prevalence of hemlock throughout eastern forests has been dramatically reduced from what it was before European settlement (before 1750). In Michigan and Wisconsin, for example, 99% of the hemlock forests present before European settlement have been eliminated (Mladenoff 1996). In Pennsylvania, more than 70% of mature hemlock trees were cut down during the 1800's and early 1900's to provide tannin (from hemlock bark) to the leather tanning industry (Whitney 1990). Currently, most mature eastern hemlock forests are in New England, although Great Smoky Mountains National Park contains substantial areas of old-growth hemlock forests (Johnson et al. 2000). Eastern hemlock is the most shade tolerant tree species in North America, capable of surviving underneath a shaded forest canopy for as long as 350 years (Quimby, 1996). Hemlock trees that successfully grow into the forest canopy can live for more than 800 years. Because it is so shade tolerant and long-lived, hemlock is a late successional (or "climax") tree that can dominate a forest for centuries. However, eastern hemlock trees have very shallow roots, and so are limited to moist areas and are very vulnerable to drought.Eastern hemlock forests create distinctive microclimates and provide important habitat for a wide variety of wildlife. In the Northeast, 96 bird and 47 mammal species are associated with hemlock forests (Yamasaki et al. 2000). Of these, at least eight species of birds and ten species of mammal have strong ecological linkages with hemlock forest habitat. Examples of birds include black-throated green warbler, blackburnian warbler, blue-headed vireo, winter wren, red-breasted nuthatch, ruffed grouse, and the northern goshawk. Examples of mammals include black bear, bobcat, snowshoe hare, red squirrel, and southern red-backed vole. Hemlock is well known as important winter habitat for white-tailed deer. Hemlock forests can also be a critical factor in supporting native brook trout populations, by maintaining cool stream temperatures and stable flows (Evans et al. 1996, Snyder et al. 1998).
1.2.2 HWA and Decline of Eastern Hemlock Forests Hemlock woolly adelgid (HWA), is a very small, aphid-like insect native to Japan. HWA is an "exotic" species, not native to the U.S. HWA was first reported in the western U.S. (Oregon) in 1924 (McClure 1987). HWA was first reported in the eastern U.S. in the mid-1950's near Richmond, VA (Souto et al. 1996). In the U.S., HWA feeds only on hemlock tree species (Tsuga spp.) (McClure 1987). The two species of hemlock trees native to the western U.S., western hemlock (Tsuga heterophylla) and mountain hemlock (Tsuga mertensiana), are not noticeably affected by HWA. In contrast, the two species of hemlock trees native to the eastern U.S., eastern hemlock (Tsuga canadensis) and Carolina hemlock (Tsuga caroliniana) are often severely defoliated and killed by HWA. In Connecticut, McClure (1991a) concluded that HWA often kills eastern hemlock trees within five years of infestation. All ages and sizes of eastern hemlock trees are susceptible to damage from HWA. As of 1999, the USDA Forest Service had documented HWA in eleven eastern states from North Carolina to Massachusetts. At Shenandoah National Park in Virginia, approximately 75% of the hemlock trees evaluated have suffered defoliation and mortality related to HWA infestations (Akerson and Hunt 1998). In New Jersey, 44% of the hemlock resource has been estimated to be moderately to severely impacted by HWA (Onken 1999a). HWA completes two generations a year, and has very high reproductive rates. One generation of HWA actively feeds through the winter, and lays most of its eggs in March and April. The following generation of HWA actively feeds through the spring, and lays most of its eggs during June. HWA reproduces asexually (parthenogenetically); females produce offspring genetically identical to themselves, without fertilization by males. HWA populations are composed almost entirely of females, and each female can produce up to 300 eggs (McClure 1987). Natural mortality in HWA populations is commonly 30 to 60 percent, but the reproduction potential remains exponential. Significant natural mortality of HWA in the eastern U.S. is generally attributed to two causes: (1) an extended period(s) of cold winter temperatures, and/or (2) a reduction in food quality or quantity associated with the decline in health of the host tree (McClure 1991a). Since becoming established in the eastern U.S. 40 to 50 years ago, HWA populations have not been controlled by any existing predators, parasites, or diseases (Wallace and Hain 2000). The destructive effects of HWA infestations on hemlock forests are strongly exacerbated by many other environmental factors. These include climatic changes, acidic deposition, high densities of white-tailed deer, and invasions of other exotic insects (e.g. elongate hemlock scale Fiorinia externa, gypsy moth Lymantria dispar), and exotic plants. Climatic changes have probably contributed to hemlock decline in the Mid-Atlantic region and southern New England in several ways. The recent series of mild winters has allowed HWA populations to increase tremendously, unchecked by winter mortality. The recent series of severe droughts has stressed hemlock trees over large areas, and made them more vulnerable to insects like HWA and hemlock borer beetles (see section 1.2.5). Chronic deposition of high nitrates (part of "acid rain") may be accelerating HWA population growth (McClure 1992), and at the same time stressing trees and degrading soil fertility. High densities of white-tailed deer have greatly changed the vegetation and interfered with, or even prevented, tree regeneration in many eastern forests. As hemlock forests are affected by all these factors, exotic plants like "tree-of-heaven" (Ailanthus altissima), Japanese barberry (Berberis thunbergii), and Japanese stilt-grass (Microstegium vimineum) can invade and replace the native plants (Orwig and Foster 1998). 1.2.3 Importance of Hemlock Forests at DWGNRA Hemlock forests contribute greatly to the ecological, aesthetic, and recreational values of the park. Eastern hemlock is an important component of the forest canopy of 141 forest stands covering approximately 2,800 acres (about 5%) of the recreation area (Myers and Irish 1981; Young et al. 1998). Many of these hemlock stands were designated as "Outstanding Natural Features" having "high intrinsic or unique values" in the General Management Plan (1987) for the recreation area. Many scenic waterfalls are associated with hemlock stands at DWGNRA, and recreational activities like hiking, trout fishing, bird watching, and general "sight-seeing" and picnicking are very popular and concentrated in these areas. Notable examples of important scenic and recreational areas situated in hemlock forests on the Pennsylvania side of the park include Dingmans Creek and associated trails and Visitor Center; Adams Creek and Toms Creek (both state designated "exceptional value" trout streams); Raymondskill Creek and associated trails and restrooms; Hornbecks Creek; Tumbling Waters and Spackmans Creek (both important to the Pocono Environmental Education Center). Examples on the New Jersey side of the park include VanCampens Brook (a "blue-ribbon" trout stream) and associated picnic area, Buttermilk Falls, Copper Mine ravine, and Dunnfield Creek. Recent studies conducted in the recreation area have documented many distinctive characteristics of hemlock forests and ecosystems. Hemlock forests are generally older than hardwood forests in the park (Sullivan et al. 1998). Hemlock forests create very deep shade, allowing only about 5% of incident sunlight to reach the forest, and plants are sparse beneath the forest canopy (Battles et al. 2000). Yet, 316 species of plants were documented in the hemlock forests at Adams Creek and VanCampens Brook, including 122 species of flowering herbs and 123 species of mosses and liverworts (Battles et al. 2000). Many species of birds, small mammals, amphibians, and insects inhabit hemlock forests, and a number of these depend on these forests for their existence in this region. Birds such as blackburnian warblers (Dendroica fusca), black-throated green warblers (Dendroica virens), and blue-headed (a.k.a. "solitary") vireos (Vireo solitarius)occur almost exclusively in hemlock forests of the park (Evans et al. 1996). Hemlock forests also provide important habitat for other birds of the area, such as winter wrens (Troglodytes troglodytes), red-breasted nuthatches (Sitta canadensis), golden-crowned kinglets (Regulus satrapa), Acadian flycatchers (Empidonax virescens), Louisiana waterthrushes (Seiurus motacilla), and saw-whet owls (Aegolius acadicus). Hemlock ravines in the park support more than 15 species of amphibians more than 12 species of small mammals; relatively high numbers compared to many other forest types in the region (Sciascia and Pehek 1995). Two state listed rare species of small mammals, the Northern water shrew Sorex palustris, and the pygmy shrew Sorex hoyi, inhabit hemlock ravines in the park (Sciascia and Pehek 1995). At least 152 species of ground invertebrates also occur in park hemlock forests (Schrot 1998). The hemlock angle moth (Semiothisa fissinotata) depends entirely on hemlock for its existence, and this moth almost certainly inhabits the hemlock forests of the recreation area (Schweitzer 1994). Small streams in hemlock forests are three times more likely to support native brook trout populations than similar streams in hardwood forests in the park (Snyder et al. 1998). Thus, the Pennsylvania State fish, brook trout, is ecologically linked to the Pennsylvania State tree, eastern hemlock. Evans et al. (1996) showed that streams cool by as much as 50C (90F) during the summer while flowing through hemlock ravines in the park, and this cooling is critical for brook trout survival in many streams. Snyder et al. (1998) showed that small streams in hemlock forests are typically 10C-20C (20F-3.50F) cooler in the summer than similar streams in hardwood forests in the park. Furthermore, hemlock forest streams typically support about 65 species of aquatic insects, compared to only about 35 species in hardwood forest streams. About 15 species of aquatic insects seem to occur almost exclusively in hemlock forest streams in the park (Snyder et al. 1998). 1.2.4 The Threat of HWA and Hemlock Decline at DWGNRA HWA now threatens the ecological, aesthetic, and recreational values associated with these hemlock forests at DWGNRA. HWA was first detected within the boundaries of the recreation area in 1989 at Dunnfield Creek (New Jersey) and on Mount Minsi (Pennsylvania) (Millington 1989). Since 1989, HWA has spread throughout the recreation area. In 1992, Donkey's Corner ravine was already heavily infested with HWA. In 1995, HWA was found at 30 of 58 sites (52%) surveyed throughout the recreation area. By 1999, HWA was found at all (100%) of the same 58 sites surveyed (Figure 1). Most of the hemlock trees inspected at annual monitoring sites were infested with HWA, and all the trees at Mount Minsi, Dunnfield Creek, and Donkeys Corners were infested in 1999 (Figure 2). More than half the hemlock trees evaluated at Mount Minsi, and three-quarters of the hemlock trees at Dunnfield Creek and Donkeys Corners were either dead or defoliated in 1999 (Figure 2). Defoliation and mortality of eastern hemlock trees within the recreation area has been apparent for several years at many HWA infested sites along the Kittatinny ridge, including Mount Minsi, Dunnfield Creek, Coppermine ravine, and Donkey's Corner. An aerial survey of the recreation area conducted by the USDA Forest Service in 1999 identified 19 sites with noticeable hemlock discoloration and mortality. Most of these sites are on the Kittatinny Ridge where HWA infestations have been present the longest. Severe droughts during the past several years, including 1999, have stressed many hemlock trees in the park, and greatly reduced their ability to withstand HWA infestations. 1.2.5 The Additional Threat of Hemlock Borer Beetle at DWGNRA Infestations of hemlock borer beetle (Melanophila fulvoguttata) have recently been discovered in the park. This is a native species of beetle (family Buprestidae) that usually only attacks severely stressed hemlock trees, not healthy trees. In the past, severely stressed trees were relatively rare at any one time. However, HWA infestations and drought have now severely stressed many hemlock trees over large areas, and these trees are vulnerable to attack by hemlock borer beetles. After hemlock borer beetles become abundant, woodpeckers chip the bark off infested trees as they hunt for (and eat) these beetles. The boles (trunks) of hemlock trees attacked this way have a very distinctive rusty-red appearance. Although HWA infested trees might otherwise survive for many years, they die within a year or two after being attacked by borer beetles. Furthermore, hemlock borer beetles can become so abundant during these "outbreaks" that they attack and severely injure or even kill otherwise healthy hemlock trees. Since October 1999, it has become apparent that thousands of hemlock trees in the area from Milford, PA south to the Pocono Environmental Education Center have been attacked by hemlock borer beetles and will soon die. Specific sites include Raymondskill Creek, Conashaugh Creek, Dry Brook, Adams Creek, Dingmans Creek, Hornbecks Creek, and Spackmans Creek.1.3 Opportunity for Action
In 1992, McClure discovered Pseudoscymnus tsugae, a tiny black "ladybird beetle" that feeds exclusively on HWA in Japan (Sasaji and McClure 1997). Subsequently, the beetle was brought to the U.S., screened in quarantine, and evaluated to determine its suitability as a biocontrol agent for HWA in this country. Extensive laboratory and field tests indicated that P. tsugae was a very effective predator of HWA, and an excellent candidate for biocontrol of HWA (Cheah 1998). In 1995, the USDA Animal and Plant Health Inspection Service (APHIS) issued Permit Number 950678 to the CT Agricultural Experiment Station to release these beetles in Connecticut. In 1997, staff at the New Jersey Department of Agriculture's Phillip Alampi Beneficial Insect Laboratory began mass rearing of this beetle. In 1998, 75,500 of these beetles were released in 15 hemlock forests infested with HWA in New Jersey (Mayer et al. 1998). In 1999, a similar number of beetles were released in New Jersey (Mark Mayer, personal communication). In addition, approximately 10,000 beetles were released at one site in each of nine other states (about 90,000 beetles total), through the support of the USDA Forest Service (Onken 1999a). The 1999-release site in Pennsylvania was in Franklin County (south central PA), more than 150 miles from the recreation area.
Results from these releases have shown that the beetles have successfully: (1) reduced HWA populations in the immediate vicinity of release sites, (2) survived throughout the year, and (3) reproduced in the forests (McClure et al. 2000, Mayer et al. 1998). However, results from these releases have not yet shown that the beetles are capable of successfully: (1) suppressing HWA populations over many years to levels that allow eastern hemlock trees to survive, grow, and reproduce, or (2) dispersing and reproducing beyond the immediate release site.
In November of 1999, the superintendent of Delaware Water Gap National Recreation Area requested that the USDA Forest Service make these beetles available for release in the park during spring or early summer of 2000, pending the outcome of an Environmental Assessment (Laitner 1999). The Forest Service responded that, if beetles were available from rearing facilities, it would provide them to the recreation area, should the NPS decide in favor of releasing the beetles (Onken 1999b). Staff at the Philip Alampi Beneficial Insect Laboratory also offered to provide beetles for one release site within the New Jersey side of the recreation area (Mark Mayer, personal communication).
1.4 Decisions to Be Made
The decisions to be made by the NPS, based on the information included in this Environmental Assessment are:
The responsible official for making these decisions is:
Ms. Marie Rust
National Park Service
Northeast Regional Director
Philadelphia Support Office
200 Chestnut Street
Philadelphia, PA
The regional director may delegate her decision-making authority to:
Mr. William Laitner
Superintendent
Delaware Water Gap National Recreation Area
Bushkill, PA 18324
The responsible official will make these decisions on or about May 24, 1999, to ensure adequate time to prepare for the beetle releases, if the proposed alternative is chosen. If no EIS is required and the proposed action is approved, the decision will be documented in a Finding of No Significant Impact (FONSI). Should the NPS decide that an EIS is needed or choose not to conduct the proposed action, P. tsugae beetles would not be released in the recreation area in the year 2000. However, beetles will continue to be released by the New Jersey Department of Agriculture on nearby lands that are managed by the state of New Jersey.
1.5 Scope of this Environmental Assessment
1.5.1 Related NEPA Documents
As part of the decision-making process for previous releases of P. tsugae beetles in the eastern U.S., three previous EAs and FONSI's were completed by other agencies. For the initial releases in Connecticut, the USDA Animal and Plant Health Inspection Service completed an EA titled "Field Release of a Nonindigenous Lady Beetle, Pseudoscymnus sp. (Coleoptera: Coccinnellidae), for Biological Control of Hemlock Woolly Adelgid, Adelges tsugae (Homoptera: Adelgidae)," and issued a FONSI in 1995. For additional releases in Connecticut, the Connecticut Agricultural Experiment Station completed an EA titled "Establishing Pseudoscymnus tsugae (Coleoptera: Coccinellidae) as a Biological Control Agent for Hemlock Woolly Adelgid," and the USDA Forest Service subsequently issued a FONSI in 1998. For releases in ten states, the USDA Forest Service completed an EA "For the Release and Establishment of Pseudoscymnus tsugae (Coleoptera: Coccinellidae) as a Biological Control Agent for Hemlock Woolly Adelgid," and subsequently issued a FONSI in 1999. Also, in a letter to the USDA Forest Service, the U.S. Fish and Wildlife Service concurred that the release of this beetle would not impact any federally listed Threatened or Endangered Species. These documents are incorporated to the present EA by reference, and copies of these documents may be obtained by request.
1.5.2 Scoping Activities and Issues
An NPS interdisciplinary team met on 9 December 1999, in order to discuss issues relating to HWA, hemlock decline, management alternatives at DWGNRA - especially the possibility of releasing P. tsugae beetles. NPS staff on the team included an Ecologist, a Biologist, an Environmental Planner, the regional Integrated Pest Management Coordinator, and the Park Planning & Natural Resources Group Manager from the Philadelphia Support Office. At that meeting, the interdisciplinary team made initial plans for preparing this EA.
Before preparing this EA, a wide variety of people outside of the NPS were contacted to get their ideas and concerns about HWA, hemlock decline, and especially the possibility of releasing P. tsugae beetles at DWGNRA. Discussions were held during the fall of 1999 with environmental classes from Penn State University - Altoona, Orange County Community College (NY), and Wallenpaupack Area High School (Hawley, PA). Numerous scientists with relevant expertise (see chapter 4) were contacted individually by telephone and electronic mail in order to identify potential issues, especially those related to the release of beetles. Later the Pike County, PA and Monroe County, PA Conservation Districts were contacted. Many of these people expressed great concern about the loss of eastern hemlock forests. As a result of these contacts and discussions, four main issues were identified for detailed consideration in this EA (see section 1.5.3 below).
1.5.3 Issues Considered in Detail
Issue 1: P. tsugae could become a nuisance in human habitations.
Issue 2: P. tsugae could adversely impact non-target species, in particular, alder aphids and the harvester butterfly.
Issue 3: P. tsugae beetles may not suppress HWA populations effectively at the forest stand level or over the long-term.
Issue 4: Continuing decline of eastern hemlock forests infested with HWA, and associated issues:
2.0 ALTERNATIVES, INCLUDING THE PROPOSED ACTION
This chapter describes all the alternatives considered, including those that were dismissed as infeasible. Two alternatives are considered in detail: (1) "No Action," and (2) the Proposed Action, releasing beetles. The main environmental consequences expected from each of these two alternatives are summarized very briefly.
2.1 Alternatives Considered, but Dismissed
2.1.1 Ground spraying with horticultural oils or insecticidal soaps
This method of treatment can be effective in situations where there is access to the trees for ground spraying equipment, including pumping trucks with high-pressure hoses, and the entire crown of each tree can be saturated with the spray. Such access is not readily available in the remote and rugged terrain of the hemlock forests of concern at DWGNRA. Furthermore, these oils and soaps are somewhat toxic to aquatic organisms, and should not be sprayed near surface waters. But protection of the hemlock forests adjacent to streams at DWGNRA is particularly important, because these are the hemlock forests most important to recreation and ecology in the park. Therefore, this alternative was considered infeasible and was dismissed.
2.1.2 Aerial spraying
Aerial spraying with horticultural oils or insecticidal soaps is not an effective treatment, because it fails to provide the needed "saturation" coverage of each tree crown, and could affect surface waters. Aerial spraying with more toxic insecticides (e.g. "malathion" or "diazinon") would have very significant, unacceptable impacts on a wide range of non-target insects and other animals. Therefore, this alternative was considered infeasible and was dismissed.
2.1.3 Systemic Insecticides
Several types of systemic insecticides can be injected (e.g. "bidrin" or "metasystox-R") or implanted (e.g. "acephate") into hemlock trees, and another ("Merit") can be applied to the soil around hemlock trees. These insecticides are absorbed and transported by the vascular system of the tree to feeding adelgids, and will effectively suppress HWA populations. However, none of these methods are at all practical for the long-term control of HWA populations in tens, hundreds, or thousands of acres of hemlock forests. Treatments must be applied locally, one tree at a time, and must be repeated at least every two or three years to be effective. Repeated injections and implants cause significant damage to trees over time. All these products are quite toxic, and if applied on a large scale would pose substantial risks to non-target organisms. Soil injections over large areas would threaten non-target ground arthropods, and in areas near streams or seeps, threaten non-target aquatic and semi-aquatic arthropods. Therefore, this alternative was considered infeasible and was dismissed.
2.1.4 Pheromone traps, or other methods of disrupting reproduction
Because HWA reproduces asexually (populations are entirely parthenogenetic; females reproduce without males), it is not possible to disrupt reproduction through pheromone traps or other, similar methods. Therefore, this alternative was considered infeasible and was dismissed.
2.1.5 Release of a biological control other than P. tsugae beetles
At the present time, P. tsugae is the only biological control agent potentially effective against HWA that has been permitted by the Animal and Plant Health Inspection Service (APHIS) for release. Research to find and evaluate other potential HWA biocontrols is continuing. Most promising among these are two species of lady beetle from China, Scymnus (Neopullus) sinuanodulus and Scymnus (Neopullus) ningshanensis, currently being evaluated by Montgomery and Havill (1999). A beetle species from British Columbia, Canada, named Laricobius nigrinus is another potential HWA biocontrol under investigation (Salom et al. 1999, Zilahi-Balogh et al. 2000). Sometime in the future, one or more of these species may be approved for release by APHIS. At present, however, none of these species are approved, and their eventual approval is uncertain and speculative. The goal of the NPS is prevent the decline of hemlock forests in the recreation area as soon as possible and to the greatest extent possible. Therefore, waiting for the possible approval of these other species at some time in the future was not considered a viable alternative, and was dismissed.
2.2 Alternatives Considered in Detail
Because all the above alternatives were considered infeasible, this EA considers only two alternatives in detail: (1) No Action, and (2) the Proposed Action, releasing P. tsugae beetles in the park (the preferred alternative). This section briefly summarizes these alternatives and their expected consequences.
2.2.1. Alternative 1: No Action
Under the "no action" alternative, the NPS would not release any P. tsugae beetles in the park. Beetles released very near the park by the New Jersey Department of Agriculture (Figure 1) might become established, and eventually disperse and colonize the park. However, results from beetle releases in Connecticut since 1996 have not yet provided any evidence of successful dispersal beyond the immediate release site (McClure et al. 2000). Thus, beetle dispersal and colonization of park forests from New Jersey State release sites seems extremely unlikely to occur within the next several years. Therefore, HWA populations in the park would be unaffected for at least the next several years (or more), and hemlock tree decline and mortality would be expected to continue throughout the park. Existing infestations of hemlock borer beetles would be expected to expand rapidly, killing many if not most hemlock trees already stressed by HWA and recent severe droughts. Extensive hemlock decline and mortality would be likely, and would have major adverse impacts on park ecosystems, aesthetics, recreation, and management (see section 3.4).
Monitoring of hemlock tree health (crown conditions) and HWA infestations in the park would continue as it has since 1993. In addition, surveys would be completed within the park for the hemlock angle moth (Semiothisa fissinotata), which is dependent on hemlock trees. Efforts would also be made to find P. tsugae beetles that might eventually disperse from the New Jersey release sites into the park.
Chemical suppression of HWA populations of selected hemlock trees in appropriate, accessible locations in the park could be conducted under this "no action" alternative. These treatments could be applied in order to maintain live hemlock trees near visitor centers, restrooms, picnic areas, parking lots, residential and historic structures, and heavily used trails (e.g. at Dingmans and Raymondskill). However, such treatments would not address the goal of preventing continuing hemlock decline and mortality in large forested areas of the park.
2.2.2. Alternative 2: Release P. tsugae Beetles (Proposed Action)
The proposed action is to release laboratory-reared, predatory "Japanese lady beetles" (Pseudoscymnus tsugae) in hemlock forests DWGNRA. Beetle releases during May or June, 2000 are proposed for two sites, one in New Jersey and one in Pennsylvania. The proposed New Jersey release site is the hemlock forest adjacent to VanCampens Brook, between Millbrook Village and "Blue Mountain Lakes Road" in northwest Warren County and southwest Sussex County. The proposed Pennsylvania release site is the hemlock forest adjacent to Adams Creek, between U.S. Route 209 and State Route 2001 in Pike County (Figure 1). The New Jersey Department of Agriculture's Beneficial Insect Laboratory would provide and release beetles at the New Jersey site, and the U.S. Department of Agriculture (USDA) Forest Service would provide and release beetles at the Pennsylvania site. Approximately 10,000 beetles would be released at each site.
Proposed beetle releases in the year 2000 are limited to two sites for several reasons. First, at most 20,000 beetles would be available for release within the park (Mark Mayer and Brad Onken, personal communication). Second, protocols established by the USDA Forest Service for conducting and evaluating the releases specify release of 10,000 beetles at each site. Third, established protocols require release sites to meet certain criteria, including a predominance of hemlock trees of a variety of sizes and ages in good health, a minimum stand size of 10 acres, and a recent and moderate level of HWA infestation. The two proposed release sites meet these criteria, but many of the other HWA infested forests in the park do not. Finally, monitoring HWA and beetle populations and hemlock tree health according to established protocols at each release site for at least three years entails substantial organizational commitments. Additional releases of P. tsugae beetles in the park would be possible in future years under this alternative, depending on beetle availability and the results of monitoring.
Under the proposed alternative, the NPS would coordinate with the USDA Forest Service and follow established protocols to monitor and evaluate the beetle releases for at least three consecutive years following release. Monitoring would be conducted to determine the survival, establishment, and dispersal of the beetle populations, and the effectiveness of the beetles in reducing hemlock woolly adelgid (HWA) populations and protecting hemlock tree health at a forest stand level. The NPS would prepare annual reports, summarizing results from the previous year(s), by June of 2001, 2002, and 2003. In addition, the NPS would complete surveys within the park for three species of insects: (1) the hemlock angle moth (Semiothisa fissinotata), (2) the woolly alder aphid (Prociphilus tesselatus), and (3) the harvester butterfly (Feniseca tarquinius). Monitoring of hemlock tree health (crown conditions) and HWA infestations in other areas of the park would also continue, as it has since 1993.
Chemical suppression of HWA populations of selected hemlock trees in appropriate, accessible locations in the park could also be conducted under this alternative. Chemical treatments could be applied in order to maintain live hemlock trees near visitor centers, restrooms, picnic areas, parking lots, residential and historic structures, and heavily used trails (e.g. at Dingmans and Raymondskill). However, such treatments would not address the goal of preventing continuing hemlock decline and mortality in large forested areas of the park.
2.2.3 The Environmentally Preferred Alternative
The Environmentally Preferred Alternative is the alternative that best protects, preserves, and enhances historic, natural, and cultural resources and causes the least damage to the biological and physical environment. After careful consideration of the environmental consequences of the alternatives (chapter 3, below), Alternative 2, release of P. tsugae beetles, was identified as the Environmentally Preferred Alternative.
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3.0 ENVIRONMENTAL CONSEQUENCES
This chapter describes the expected and possible direct, indirect, and cumulative effects of each of the two alternatives on the natural and human environment of the recreation area. It focuses on, and is organized in accordance with, the four main issues identified in section 1.5.3.
3.1 Issue 1: Possible Human Nuisance
Most people are familiar with the aggregating and winter shelter-seeking behavior of an introduced non-native lady beetle commonly known as the "multicolored lady-beetle" or "Halloween beetle" (Harmonia axyridis), which has become a major nuisance species. In sharp contrast to these Halloween beetles, P. tsugae beetles do not aggregate in large numbers or seek warm shelter during the fall, but instead remain in the forest (Cheah 1998). In the winter, P. tsugae beetles inhabit leaf litter on the forest floor (Cheah 1998). The behavior patterns of P. tsugae indicate it is extremely unlikely to become a nuisance to humans or human habitation.
3.1.1 Alternative 1: No Action
In the very unexpected event that P. tsugae beetles create some human nuisance, implementing this alternative (not releasing beetles in the park) would not eliminate concerns about this issue. Upwards of 250,000 to 300,000 P. tsugae beetles have already been released in 10 states, including over 150,000 beetles released within New Jersey. During the past two years, about 35,000 beetles have been released at sites in New Jersey close to, or within the boundary of the recreation area: 10,000 at Worthington State Park, 15,000 at Stokes State Forest, and 10,000 at High Point State Park (Mayer, personal communication; see Figure 1). If these beetles become established and spread, as intended, the beetles will eventually populate the recreation area. Thus, any unexpected human nuisance caused by the beetles would eventually occur at Delaware Water Gap National Recreation Area, even if the NPS did not release any beetles.
3.1.2 Alternative 2: Release Beetles (Proposed Action)
As indicated above, P. tsugae beetles are very unlikely to become a nuisance to humans or human habitations. In the very unexpected event that P. tsugae beetles create some human nuisance, releasing beetles in the park could mean that such human nuisance problems begin earlier than they would otherwise. The release and establishment of P. tsugae will have no effect on any structures or items listed on (or eligible for listing on) the National Register of Historic Places, nor will it cause loss of any significant cultural or historical resources.
3.2 Issue 2: Possible Non-target Effects
Pseudoscymnus tsugae appears to be highly specialized to feed almost exclusively on HWA or other similar adelgid species. Laboratory observations on prey choice have confirmed that P. tsugae does not attack other arthropod fauna known to be associated with hemlock (Cheah 1998). Both adult and larval stages of P. tsugae beetles feed on all life stages of HWA - eggs, nymphs, and adults. McClure has reported that in Japan, HWA is the only prey of P. tsugae beetles, and that the beetles are able to locate even very low population densities of HWA (Hennessey and McClure 1995). The ability of these beetles to locate HWA prey even when they are at very low densities is evidence that they are highly adapted to feeding on HWA. If P. tsugae beetles fed on a wide variety of prey species other than HWA, they probably would not have evolved the ability to locate HWA at low population densities (Hennessey and McClure 1995).
As an adult beetle, P. tsugae is about the size of a poppy seed -less than 2 millimeters long (less than a tenth of an inch). The small size of this beetle probably severely limits the size and variety of its potential prey. P. tsugae is a member of a sub-group of "lady-beetles" known scientifically as the tribe "Scymnini." In general, beetles in this sub-group are very small and feed on very limited kinds of prey - primarily on other very small insects known as adelgids, aphids, and scale insects. Other non-native species of beetles in this sub-group (Scymnini) have been introduced without any noticeable adverse effects on non-target species (Gordon 1985, in Hennessey and McClure 1995).
However, it should be acknowledged that these other Scymnini biocontrol beetles could have affected non-target species without such effects being noticed. In the past, only very limited research, at best, was conducted to detect non-target effects. Thus, the lack of evidence for any effect on non-target species can not be interpreted as strong evidence for the absence of any non-target effect (Simberloff and Stiling 1996, 1998).
Laboratory experiments have demonstrated that larvae and adult P. tsugae beetles can feed on two other non-native adelgid species: pine bark adelgid, Pineus strobi, and balsam woolly adelgid, A. piceae. The beetles can also feed on Cooley spruce gall adelgid, Adelges cooleyi, which may or may not be a native species.
A very preliminary study conducted by Cheah (1999) at the suggestion of Dr. Jeff Boettner indicated at least a remote possibility that P. tsugae beetles could feed on native woolly alder aphids (Prociphilus tesselatus). Moreover, these woolly alder aphids are the prey of the "harvester butterfly" (Feniseca tarquinius). Therefore, the beetles could, at least in theory, indirectly and adversely affect populations of the harvester butterfly, if they fed on and reduced populations of woolly alder aphids. But to feed on these alder aphids, P. tsugae beetles would have to migrate from hemlock forests to more open wetlands inhabited by alder shrubs (Alnus sp.) or other plants that could support woolly alder aphids. P. tsugae beetles would be most likely to attack woolly alder aphids if the aphids were available at the same time that HWA was inactive and relatively unavailable - that is, July through September. In Japan, adult P. tsugae beetles were collected from grasses at "marshy sites" during the summer (Sasaji and McClure 1997).
The harvester butterfly is not a threatened or endangered species. However, it is the only predatory butterfly (caterpillar) species native to North America, and as such is of special interest to science and conservation. The U.S. Fish and Wildlife Service has concurred that there are no known federally listed Threatened or Endangered Species that would be impacted by the release of this beetle ( E).
3.2.1 Alternative 1: No Action
If P. tsugae beetles adversely affect non-target species, such as native adelgids or woolly alder aphids, choosing this alternative (not releasing beetles in the park) would not eliminate concerns about this issue. Upwards of 250,000 to 300,000 P. tsugae beetles have already been released in 10 states, including over 150,000 beetles released within New Jersey. In the past two years, about 35,000 beetles have been released at sites in New Jersey close to, or within the boundary of the recreation area: 10,000 at Worthington State Park, 15,000 at Stokes State Forest, and 10,000 at High Point State Park (Mayer, personal communication; see Figure 1). If these beetles become established and spread, as intended, the beetles will eventually populate the recreation area. Thus, any unexpected effects on non-target species would eventually occur at Delaware Water Gap National Recreation Area, even if the NPS did not release any beetles.
3.2.2 Alternative 2: Release Beetles (Proposed Action)
If P. tsugae beetles adversely affect non-target species, such as native adelgids or woolly alder aphids, releasing beetles in the park could mean that such non-target effects begin earlier in the park than they would otherwise.
3.3 Issue 3: P. tsugae Beetles may not be Effective in Forests Long-Term
P. tsugae beetles may fail to control HWA populations in forests over the long-term for several reasons. First, they may completely fail to establish self-sustaining populations. Second, established beetle populations may not successfully grow and spread beyond the immediate release area. Third, beetle populations may become established and spread throughout the affected forests, but not maintain sufficient population densities over time to keep HWA populations below injurious levels.
3.3.1 Alternative 1: No Action
In this case, the consequences of the "No Action" alternative would be identical to those described in section 3.4.1 (below) for the issue of continued hemlock forest decline. If beetle populations from the New Jersey State release sites failed to spread and grow sufficiently to control HWA in the release site forests, they would probably not have any effects in the park, either positive or negative.
3.3.2 Alternative 2: Release Beetles (Proposed Action)
In this case, the consequences of releasing beetles in the park would be similar to those described in section 3.4.1 (below) for the issue of continued hemlock forest decline. If beetles released in the park failed to spread and grow sufficiently to control HWA in the release site forests, they would probably not have any positive or negative effects.
3.4 Issue 4: Continued Decline of Hemlock Forests
3.4.1 Alternative 1: No Action
Implementation of this alternative, not releasing beetles, would fail to address concerns about continued hemlock decline and mortality in the recreation area. If the HWA biocontrol beetles released by the New Jersey Department of Agriculture become established and spread, as is intended, they would eventually populate the recreation area. However, it is very unlikely that the beetles would become established and spread to hemlock forests in the park soon enough to suppress HWA effectively, based on evidence to date (McClure and Cheah 1999; Mark Mayer personal communication; Brad Onken personal communication). Thus, only severe cold weather and hemlock decline and mortality would limit HWA populations (see section 1.2.2) in the park. Hemlock trees would continue to decline and die throughout HWA infested areas of the park.
Hemlock borer beetles would probably attack and kill increasing numbers of hemlock trees stressed by HWA and recent severe droughts. Mortality of many, if not most, of the hemlock trees over large areas would be likely within the next 10 to 15 years. Dead and dying trees would increase the risks of forest fires, and create hazard trees along roads and trails and near structures. Fallen trees would have to be cut and removed from roads and trails.
The loss of large portions of hemlock forest canopy likely to occur under this alternative would have massive adverse effects on the ecological, aesthetic, and recreational values of the park. Eastern hemlock forests could eventually be eliminated from the park entirely. If so, the hemlock angle moth would also be eliminated from the park. Affected areas would receive much more sunlight, and be hotter and drier in the summer.
Streams would be warmer, have lower water flows, and be more likely to dry-up during summer droughts. Consequently, native brook trout would be less likely to survive and reproduce in affected streams. Thus, the distribution and abundance of this important native sport fish, Pennsylvania's State fish, would be reduced in the recreation area, and opportunities to fish for it would also be greatly reduced. Opportunities to view scenic waterfalls in a shaded, majestic forest setting would also be greatly reduced.
Though aquatic insect density could possibly increase in affected streams, the number of aquatic insect species would probably decline by 35 percent or more (Snyder et al. 1998). Increased light and nutrient levels reaching affected streams could lead to increased nuisance algal blooms (Evans 1996, Yorks et al. 2000). Eventually, dead and fallen hemlock logs would accumulate on the forest floor and in stream channels. In streams these logs would create excessive debris dams, destabilizing the stream channels and increasing the chance of extreme flood damage (due to "debris flows" and scouring) to roads, trails and structures. Erosion and sedimentation of stream channels would increase, further reducing habitat for brook trout and other fish and aquatic insects.
Mature, canopy level hemlock trees would eventually be replaced primarily by deciduous trees, especially black birch (Betula lenta) and red maple (Acer rubrum) (Battles et al. 2000, Orwig and Foster 1998). White pine (Pinus strobus) would also probably spread and become more abundant in the approximately 60% of hemlock stands where it is already present (Sullivan et al. 1998). In the process, hundreds or thousands of these sapling trees would compete for the space vacated by each mature hemlock tree. Rather than being open and spacious, much of the lower forest environment would become a thicket of saplings for several decades. Existing patches of hay-scented fern (Dennstaedtia punctilobula) would expand over larger areas of forest floor, especially if white-tailed deer browsing inhibited tree regeneration. Areas colonized by this fern would not revert to forest without direct management action. The variety and abundance of mosses and liverworts now present in these forests would decrease. Invasive exotic plants, such as "tree-of-heaven" (Ailanthus altissima), Japanese barberry (Berberis thunbergii), and Japanese stilt-grass (Microstegium vimineum) would spread through affected forests (Orwig and Foster 1998).
Populations of several species of birds would decline, especially blackburnian warblers (Dendroica fusca), black-throated green warblers (Dendroica virens), and blue-headed vireos (Vireo solitarius) (Evans et al. 1996). Populations of many other birds would likely also be adversely impacted, including winter wrens (Troglodytes troglodytes), red-breasted nuthatches (Sitta canadensis), golden-crowned kinglets (Regulus satrapa), Acadian flycatchers (Empidonax virescens), Louisiana waterthrushes (Seiurus motacilla), northern goshawks (Accipiter gentilis), and saw-whet owls (Aegolius acadicus) (Benzinger 1994, Yamasaki et al. 2000). Populations of downy woodpeckers (Picoides pubescens), hairy woodpeckers (Picoides villosus), and pileated woodpeckers (Dryocopus pileatus) would increase for several decades.
Wetlands and Floodplains: Many natural hemlock stands grow in riparian (streamside) areas that may be classified as wetlands or floodplains. As indicated above, the native flora, fauna, and ecosystem characteristics of these areas would be severely impacted under the No Action alternative.
Threatened and Endangered Species: Despite the severe and extensive environmental impacts expected under the No Action Alternative, no federally listed or candidate species would be affected. A number of state listed species of special concern could be adversely impacted, including the northern goshawk, saw-whet owl, northern flying squirrel (Glaucomys sabrinus), Northern water shrew, and the pygmy shrew.
3.4.2 Alternative 2: Release Beetles (Proposed Action)
P. tsugae has been shown to be an aggressive HWA predator and would be expected to help reduce HWA populations in the vicinity of the two release sites. It is not known however, if the beetles would be able to reproduce and spread quickly enough to maintain HWA populations low enough to prevent loss of hemlocks on a forest stand scale. Even if the proposed action were successful, only the release site forests would benefit within the next several years. P. tsugae beetles could be released at additional sites, such as Dingmans Creek, in future years. Hemlock decline and mortality would be expected to continue in other hemlock forests throughout the park. It is already "too late" for any effective action at many of these other areas, and they would be expected to experience the same consequences described above (section 3.4.1) for the No Action alternative.
Wetlands and Floodplains: The release and establishment of P. tsugae would not be expected to impact any native organism associated with wetlands or floodplains. Once established, P. tsugae is expected to protect riparian hemlock trees and forests by reducing HWA populations. Thus, a statement of finding regarding wetlands is not necessary.
Threatened and Endangered Species: The U.S. Fish and Wildlife Service concurred that the release of P. tsugae beetles would not impact any federally listed Threatened or Endangered Species. The release and establishment of P. tsugae would also not have any adverse impacts on state listed threatened or endangered species.
3.5 Cumulative ImpactsAs described previously (at the end of section 1.2.2), the destructive effects of HWA infestations on hemlock forests are strongly exacerbated by many other environmental factors. These include climatic changes, acidic deposition, high densities of white-tailed deer, other forest insects, and invasive exotic plants. Some of these environmental factors (e.g. climate) increase the rate and extent of eastern hemlock decline and mortality. Other factors (e.g. invasive exotic plants) prevent recovery of native forest species following hemlock decline and mortality. The cumulative interaction of all these factors: (a) greatly increases the speed and likelihood of mortality of hemlock forests, and (b) greatly decreases the likelihood of recovery or restoration of native hemlock forests.
During the past two years, the New Jersey Department of Agriculture released about 35,000 beetles very near the boundary of the recreation area: 10,000 at Worthington State Park, 15,000 at Stokes State Forest, and 10,000 at High Point State Park (Figure 1). If these beetles become established and spread, as intended, they will eventually populate the recreation area. Consequently (as described previously in sections 3.1, 3.2, and 3.4), the park would eventually experience any unexpected adverse consequences of the beetles, even if the National Park Service did not release any of these beetles. Yet, it is extremely unlikely that these beetles would disperse into DWGNRA soon enough to provide any positive benefit to the park in the form of controlling HWA populations (see section 2.2.1).
{back to Table of Contents}4.0 LIST OF AGENCIES AND PERSONS CONSULTED
This Environmental Assessment was prepared by Richard A. Evans, Ecologist, U.S. Department of Interior, National Park Service, Delaware Water Gap National Recreation Area. Substantial assistance was provided by the following individuals:
4.1 National Park Service
Dr. Terry Cacek, NPS Integrated Pest Management Coordinator.
David Reynolds, Park Planning & Natural Resources Group Manager, Philadelphia Support Office
Cynthia Wilkerson, Outdoor Recreation Planner, Philadelphia Support Office
Wayne Millington, Northeast Regional Integrated Pest Management Coordinator
Jacki Katzmire, Natural Resource Specialist, DWGNRA
Alan Ambler, Biologist, DWGNRA.
4.2 Other Natural Resource Professionals
Brad Onken, USDA Forest Service, Northeastern Area State and Private Forestry.
Mark Mayer, New Jersey Department of Agriculture, Philip Alampi Beneficial Insect Laboratory.
Susan Beecher, Pike County (PA) Conservation District Manager
Craig Todd, Monroe County (PA) Conservation District Manager
4.3 External Scientists
Dr. Jeff Boettner, Department of Entomology, University of Massachusetts, Amherst. Entomologist researching non-target effects of biocontrols (Boettner et al. In press).
Dr. Peter Kareiva, National Marine Fishery Service, Seattle, Washington. Risk assessment expert who has also conducted research on coccinellid ("lady beetle") ecology.
Dr. Svata Louda, School of Biological Sciences, University of Nebraska, Lincoln. Researcher and author of numerous critical studies of biocontrols (see Louda et al. 1997, and Gassmann and Louda, In press).
Dr. John Obrycki, Department of Entomology, Iowa State University, Ames; currently Invasive Species Coordinator for the U.S. Department of Agriculture - CSREES. Entomologist with special expertise in "lady-beetles" (Coccinellidae), and their use as biocontrols (Obrycki and Kring In press).
Dr. Dale Schweitzer, The Nature Conservancy, New Jersey. Expert in butterflies and moths, familiar with the area (Schweitzer 1996).
Dr. Dan Simberloff, Department of Ecology and Evolutionary Biology, University of Tennessee-Knoxville. Prominent ecologist critical of biocontrols (see Simberloff and Stiling 1996, 1998).
Dr. Roy VanDrieshe, Department of Entomology, University of Massachusetts, Amherst. Entomologist with special concern for effects of invasive non-native species (see Van Driesche and Van Driesche In Press).
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5.0 REFERENCES
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Gassmann, A., and S.M. Louda. In press. Rhinocyllus conicus: Evaluation and subsequent ecological impacts in North America. In "Evaluating Indirect Ecological Effects of Biological Control," J. Waage and J. Scott, editors. International Organization for Biological Control and Complexe International de Biologique. Agropolis, Montpellier, France.
Godman, R.M. and K. Lancaster. 1990. Tsuga canadensis (L.). Carr., eastern hemlock. In: R.M. Burns and B. H. Honkala, eds. Silvics of North America, vol. 1, conifers. USDA Forest Service, Agriculture Handbook No. 654. pp. 604-612.
Hennessey, R.D. and M.S. McClure. 1995. Field release of a non-indigenous lady beetle, Pseudoscymnus sp. (Coleoptera: Coccinellidae), for biological control of hemlock woolly adelgid, Adelges tsugae (Homoptera: Adelgidae). Environmental Assessment prepared by USDA Animal and Plant Health Inspection Service, Riverdale, MD, unp. report. 6p.
Jennings, D.T. 1996. Hemlock adelgid, small mammal, amphibian and terrestrial invertebrate study, 1993-1994, identification of spiders (ARACHNIDA: ARANEAE) final report. USDI National Park Service, Delaware Water Gap National Recreation Area, Bushkill, PA. 12p.
Johnson, K.D., F.P. Hain, K.S. Johnson, and F. Hastings. 2000. Hemlock resources at risk in the Great Smoky Mountains National Park. In: Proceedings of a Symposium on Sustainable Management of Hemlock Ecosystems in Eastern North America, edited by K.A. McManus, K.S. Shields, and D.R. Souto. pp.111-112.
Laitner, W. 1999. Letter (dated November 9) to Mr. John Hazel, US Forest Service, Morgantown, WV.
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Mayer, M., R. Chianese, L. Conway, and D. Palmer. 1998. Release of Pseudoscymnus tsugae (Coleoptera: Coccinellidae) on the hemlock woolly adelgid, Adelges tsugae (Homoptera: Adelgidae) in New Jersey. Annual Report. New Jersey Dept. of Agriculture, Division of Plant Industry, Phillip Alampi Beneficial Insect Laboratory, Trenton, N.J. 4pp.
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Obrycki, J.J., and T.J. Kring. In press. Predaceous coccinellidae in biological control.
Onken, B. 1999a. Environmental Assessment for the release and establishment of Pseudoscymnus tsugae (Coleoptera: Coccinellidae) as a biological control agent for hemlock woolly adelgid. USDA Forest Service, Northeastern Area, Morgantown, WV.
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Orwig, D.A. and D.R. Foster. 1998. Forest response to the introduced hemlock woolly adelgid in southern New England, USA. Journal of the Torry Botanical Society 125(1): 60-73.
Quimby, J. 1996. Value and importance of hemlock ecosystems in the eastern United States. In: S.M. Salom, T.C. Tigner, and R.C. Reardon, eds. Proceedings of the First Hemlock Woolly Adelgid Review, Charlottsville, VA, 1995. USDA Forest Service Forest Health Technology Enterprise Team-Morgantown, WV. FHTET 96-10. pp. 1-8.
Salom, S., L. Koke, and G. Zilahi-Balogh. 1999. Evaluation of Laricobius nigrinus as a potential candidate for biocontrol of HWA. Hemlock Woolly Adelgid Newsletter (4): 7. (USDA Forest Service).
Sasaji, H. and M.S. McClure. 1997. Description and distribution of Pseudoscymnus tsugae sp. nov. (Coleoptera: Coccinellidae), and important predator of hemlock woolly adelgid in Japan. Annals of the Entomological Society of America 90 (5): 563-568.
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