What is the threat?
The hemlock woolly adelgid (HWA) is a tiny insect native to Japan that drains the water and nutrient stores from the Eastern Hemlock, killing the host tree within three to nine years of infestation. It was imported in the 1950s and has since destroyed most of the southern hemlock forests, including the majority of the hemlocks of the Great Smokey Mountains. Our eastern hemlocks have no ingrained defenses, as do the hemlock species that co-evolved with the parasite.
If you see white, cottony clusters on the underside of needles on a hemlock, those are the woolly adelgids. HWA protect their eggs with a “wool-like wax” which resembles cotton and is most easily seen from November through April. The HWA itself smaller than a pinhead, and can spread from tree to tree via birds, mammals, hikers, cars, and even the wind. HWA also spread when firewood is moved, or stock from an infected nursery is brought into a previously pest-free area.
Already the HWA has caused “widespread hemlock mortality throughout the Appalachian and southern Catskill mountains,” causing “considerable ecological damage, as well as economic and aesthetic losses.” The insect has been spotted from Maine to Georgia, and is killing trees as far north as Nova Scotia.
Save Hemlock TreesWhat could be lost?
Cook Forest State Park is among the few remaining eastern forests with old-growth hemlock and white pine. Its loss would be unquantifiable, especially in light of forest decimation already inflicted upon many southern states.
Please watch an astounding short documentary by Wild Excellence Films, created pro bono out of a sense of love for the Forest and its hemlocks — Cathedral: The Fight to Save the Ancient Hemlocks of Cook Forest:
Why is it so critical to stop the hemlock woolly adelgid (HWA)?
Eastern hemlock (Tsuga canadensis) is a foundation species, upon which many other species depend for shelter and sustenance. Hemlocks along streams prevent soil erosion, filter pollutants, and keep the water clean and cool for fish and other aquatic species. In terms of ecosystem benefit, hemlocks are irreplaceable.
“The threat is huge. Hemlock is an iconic, foundation species. It’s very important ecologically and aesthetically. I’ve heard the hemlock woolly adelgid described as the worst ecological disaster, after climate change. — Mark Whitmore, Cornell entomologist
In contrast to the more deciduous forests dotted across the northeast, Cook Forest State Park – known once as “the Black Forest” — is predominately comprised of stands of Eastern Hemlock and White Pine, many of them old-growth. Some individuals in the Forest Cathedral, a National Natural Landmark area, exceed 350 years in age and are among the nation’s very tallest and largest specimens.
While the loss of hemlocks is an ecological and aesthetic disaster wherever it occurs, it would be particularly catastrophic in Cook Forest – the very character of the park would change immediately and drastically. Rather than the cool, dark, mossy “black forest” which presently supports such a unique biodiversity and stands as a last bastion of the primeval woods of the 1600s, Cook Forest could become a sad, skeletal stand comprised of the husks of giants.
What can be done?
Pesticide treatment is effective, and presently the best option for private landowners. Unfortunately, inoculating individual trees every seven years is both time-intensive and costly. Each subject tree must be located, hiked to, treated, and recorded. However, as these chemical treatments buy the trees time, there remains another hope for hemlocks.
Biological controls are likely an effective and self-perpetuating alternative to chemicals, and they’re being deployed by in many states to save these irreplaceable trees. In New York, Cornell University scientists are raising for release a beetle from the Pacific Northwest which feeds on eggs of the HWA. These “lari” beetles only feed on HWA, but they’re slow to spread. Recently, scientists have been supplementing them with the release of two silver fly species, Leucotaraxis piniperda and Leucotaraxis argenticollis, which predate on the other part of the hemlock woolly adelgid lifecycle.
To save hemlocks, the chemical and biological controls must be deployed timely and repeatedly, until balance is restored. HWA infestation progressively weakens the hemlock, and also renders the tree susceptible to other pests and stressors, including droughts.
“[T]here are many factors that lead us to believe that early efforts can contain the infestation and prevent the major loss of forest, but immediate action must occur if we are to remain optimistic.” — Melanie Manion, representative for the parks department in Ottawa County, Michigan.
The hemlock woolly adelgid is not the only foe the primeval forest faces – but it is among the most urgent, and the most dire.
How can I help?
The Pennsylvania DCNR has been consistently treating sections of Cook Forest State Park, which has been identified as a high priority site due to the density and quality of its hemlocks. However, there will be an ongoing need for funds for treatment and monitoring for the foreseeable future.
The CFC supports state efforts, and coordinates outreach programs for the individual private landowners in the area – because bugs don’t respect borders. Your donation helps save hemlocks in and around the park – anywhere in the watershed and ecosystem surrounding Cook Forest and Clear Creek State Parks.