Hemlock forest. Photo: Kent Mason

End of the Hemlocks, a Lament

The ash trees had to go. We all knew that. 

But when they went, we were still shocked and sad. Nearly 40 years after build-out, the relatively mature trees in our modest neighborhood are prized. 

Our fondness for trees doesn’t mean we knew one from the other, though, and so most of us didn’t realize that the primary thoroughfares of our neighborhood were shaded  almost entirely by ash trees.

City crews came during the day while most of us were at work and cut down dozens of trees in one particularly industrious day. The long line of stumps made me catch my breath a little when I drove back into the subdivision after work.

Our neighborhood had the look of a freshly shorn sheep, with all its cuts and bumps showing, manure clinging to its underbelly. 

Every patch of flaking stucco, every sagging gutter, every DIY disaster – all was exposed to the revealing sun.

Suddenly my neighbors, who generally don’t live in the same bubble of conservation concern in which I spend my days, were talking about a metallic green insect called the emerald ash borer (which has killed more than 10 million trees in North America) and wanted to know more about this thing called “invasive species.”

Any issue is more urgent when it hits your backyard – or your tree lawn. 

Most people have only a passing acquaintance with the nature of the place where they live and so don’t notice the dark side of invasive species – the minority of non-native plants and animals that become a significant threat to native flora and fauna.

And so if we notice it at all, we see that purple loosestrife is kind of pretty.  Zebra mussels remain underwater and go unnoticed entirely. A vast expanse of common reed grass may be choking out a local wetland but the feathery heads of the plants catch the wind with such grace it’s hard not to be captivated. 

Even Asian carp, currently the most talked-about invasive species in the Midwest, were largely ignored until they began to heave their bodies out the water and lash Illinois River anglers across their startled faces.

In my home state of Ohio, people who love natural areas are about to get such a cold, wet slap in the face in the form of the hemlock woolly adelgid – a tiny, aphid-like insect native to East Asia that is sucking the life out of hemlock trees from Georgia to Maine.

Hemlock woolly adelgid infestation. Photo: Flickr user blueridgekitties under a Creative Commons license.
Hemlock woolly adelgid infestation. Photo: Flickr user blueridgekitties under a Creative Commons license.

Brought to the U.S. about 40 years ago by imported nursery stock, the insect has spread throughout the eastern forests. And now it appears to be moving west, over the Appalachians and into places like Ohio, where it was found in 2012.

Sometimes nicknamed the “redwood of the east,” eastern hemlocks and closely related trees are slow-growing evergreens that live for hundreds of years and can grow to 150 feet tall.

Although we may not be able to name them, we recognize their deep-green branches because they are commonly found in parks, nature preserves and other protected natural areas.  

That’s because, ecologically, they provide dense, cooling shade and organic, acidic soils that create a set of plant and animal species different from the typical hardwood forests of the southern and central Appalachians.

Hemlock forests make for good trout streams and are homes to happy salamanders.

More prosaically, there are (or were) a lot of old hemlock trees in nature preserves because the loggers didn’t want them. They’re not valuable for timber and they grow along steep slopes and in deep hollows and other places where it’s just tough to log and unsuitable for building. 

During the early days of conservation, these areas were relatively pristine and the so were snatched up by organizations like The Nature Conservancy (which was, early on, sometimes derisively called the “gully and hemlock society.”)

Hemlocks set a mood, or at least they did in Robert Frost’s snowy New England:

The way a crow
Shook down on me
The dust of snow
From a hemlock tree
Has given my heart
A change of mood
And saved some part
Of a day I had rued.

I’ve rafted West Virginia’s Gauley River and agree with the guides who say the Gauley resembles a western river, not only because of its wild whitewater but also its coniferous forest canopy – up to 50 percent of the canyon’s steep slopes are covered in hemlock.  

Those trees will likely be gone before too long — victims of the adelgid,— and the guides say rafters will notice the change, even if they don’t know why the canyon looks so different.

Rafting the Gauley River. Photo: Adventures on the Gorge
Rafting the Gauley River. Photo: Adventures on the Gorge

In time, the hemlocks likely will be replaced by beeches and maples or other hardwoods.  In the short term, the opening in the forest floor may prove to be an easy conquest for Japanese honeysuckle and autumn olive, non-native, invasive species that choke out forest floors and prevent native trees from getting a start.

On Groundhog Day, I led a small group of hikers through the Clear Fork Gorge in Mohican State Park in Central Ohio. It was cold, the trail was icy and the sky overcast. But the hiking was beautiful.

Our group was thrilled by the sight of a bald eagle flying over the river, passing unnoticed by wading fishermen intent on catching trout. We stopped to rest at the base of an 80-foot frozen waterfall. 

But there was no doubt that the mood was set by the fresh snow lodged attractively in the boughs of the towering hemlock trees that line the gorge.   

As the hikers seemed so delighted by the trees, I didn’t tell them that before my grandchildren are grown, the adelgid is likely to kill those hemlocks, as they have up to 90 percent of the hemlocks in the Great Smoky Mountains National Park. As they have in The Nature Conservancy’s Greenland Gap Preserve in West Virginia. And in the Fanny Bennett Hemlock Grove, a patch of virgin wood in West Virginia’s Monongahela Forest. And as they will, eventually, in Ohio’s Clifton Gorge and the Hocking Hills.

All places where the shade of the hemlock helps set the mood of a place that remains wild.

But maybe I should have said something, because there is some hope for these trees.  Experiments with a tiny Asian beetle that is a natural predator to the adelgid show some promise in keeping the insects in check.

And scientists are working on an adelgid-resistant strain of hemlock.  In the meantime, expensive chemical treatments may keep enough hemlocks alive long enough to find a solution.

Next time I get the chance, I’ll be sure to tell people about the threats to our forests from insect pests, because there are steps each one of us can take to help prevent their spread:

Buy and burn your firewood locally. The adelgid, the ash borer, and other insects frequently hitch rides on firewood, especially when it is moved from infected areas into campgrounds in parks across the country. (Read more about this on the Don’t Move Firewood web site).

— Don’t feed the birds if you’re in an area where hemlocks are not infected. Some scientists believe the rapid spread of the adelgid throughout the east is partly to blame on migratory birds.

— Write or call your Congressional representatives and tell them that more must be done to stop the import and spread of invasive insect pests. Tell them the U.S. Department of Agriculture needs more encouragement to approve new rules and regulations that will prevent invasive insects from getting into the country, and from moving around the country once they are here.

— If you’re hiking where there are hemlocks, keep an eye out for small, fluffy white balls at the base of the needles. These are hemlock woolly adelgids. If you see them, contact your state forestry officials.

In the meantime, large stands of dead hemlock stand in mute testament to the rule of unintended consequences.

As they become more common in places near and dear to me, maybe they will move me to take more action to save them.  Maybe my fellow hikers will be moved to action. And just maybe, you’ll be moved, too.

Opinions expressed on Conservancy Talk and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of the Conservancy.

If you believe in the work we’re doing, please lend a hand.


  1. With enough foresight the vast majority of Ohio’s hemlocks can be put on life support with chemical intervention- until a viable biological control can be introduced. It is not expensive compared to the total loss of the trees and hazard reduction remediation. My company specializes in this type of work and would be glad to assist in developing a management plan. Do some research about what is happening and what works and doesn’t before the window of opportunity slams shut.

  2. In your article you mention hemlocks will be replaced by beech and maple trees. But a large area of the eastern U.S. has been affected by beech bark disease for decades and is also caused in part by non-native species. And also worsened by warmer weather from climate change. I live near the Monongahela Forest in WV and the beech trees seem to be disappearing even more rapidly than the hemlocks.

  3. Many years ago I had the privilege of seeing what I was told was a stand of virgin hemlock that were located near the Stover Creek area in North Georgia. These were enormous trees that may have required five or six people touching fingertips together to encircle their enormous trunk. This was about thirty years ago. We were told then that those majestic trees were doomed. That was a very sad thought. My feelings about it now? That’s still a sad thought, but I know there will always be something that will eventually fill the niche. I’m grateful that I had the opportunity to see something that few people will ever have a chance to see. Ultimately… man will not outsmart nature.

  4. I am in the hocking hills in Ohio for Thanksgiving. I am heartbroken. The entire area looks like there was a forest fire. There used to be a green canopy with mist everywhere. Now all of the trees are brown, dying, and the whole area looks like a war zone. The hemlock trees are dying. There are live hemlocks at the ash cave and cedar falls areas
    But everywhere else is brown and dingy. The state of Ohio treated 500 trees from the japanese bug infestation. Big deal! There must be millions of hemlock trees that are dead, beyond repair. This is a disaster. I had no idea this was going on. What a sinful crime against nature and God. It is ugly, brown, and dead.

Add a Comment