Exploring The Last Green Valley’s Eastern Hemlock Trees

Exploring The Last Green Valley’s Eastern Hemlock Trees

“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 rued.”

–“Dust of Snow,” by Robert Frost

When the hills and valleys are filled with snow and the icy grip of old man winter continues its reign throughout the land, there are still beautiful swaths of green to be found. Hemlocks are a special tree in those green, winter oasis here in The Last Green Valley National Heritage Corridor.

I grew up in a woodsy neighborhood with mostly deciduous trees, such as red oaks and red maples. A very large eastern hemlock stood out from the rest, and it’s that tree I picture when I think of my old neighborhood.

When my siblings and neighbor friends would play hide-and-seek, I would sneak under the low-hanging, long-sweeping branches of that hemlock, disappearing into my own, perfect hiding place. The thick layer of fallen needles made for a soft place to hide, and with my back to the trunk I was undetected. I can still smell the hemlock pitch and feel it’s cool shade from those childhood days.

I remember a winter hike years later when I followed deer tracks through the snow to the base of a large hemlock and discovered signs of where two or more deer had bedded down for the night. Crouching under the branches, the soft, matted spot where they had found warmth and safety became obvious.

The eastern hemlock is an important tree in New England beyond the shelter it provides. It can be found in most of our region’s habitats, from slopes and hillsides to swamps and wetlands. Shade tolerant and long-lived, it usually grows to about 70 feet, but can tower well over 100 feet, with a beautiful conical-shaped crown.

“Its lumber is fairly light in weight, touch, coarse-grained, tends to splinter and is durable underground. It is used primarily for framing, in carpentry. The inner bark of the hemlock is rich in tannic acid and was long used in leather-making…” wrote Hal Borland in “A Countryman’s Woods.”

The leaves of the hemlock are less than one inch long, flat in shape and found in two vertical rows on a stem. They are a shiny green color on top and a bluish grey on the bottom. The seed cones are oval and one-half to one inch in length.

Hemlocks are considered a keystone species, meaning they affect the habitat and other living species where they are found. When stationed next to a stream, hemlocks provide cooler shaded pools needed by trout in the summer heat. When you hike through a hemlock grove on a hot summer day you will experience a microclimate of cooler temperatures.

Of great concern for the long-term health and vitality of these beautiful trees is the threat of the hemlock woolly adelgid, a sap-sucking bug accidently introduced from Asia to the United States in the 1920s. Found just under the leaves of the eastern hemlock, the woolly adelgid is easily seen at its adult stage when it is encased in a cottony substance that protects the insect from drying out. Although some trees die within 4-5 years of infestation, many also remain in a weakened state for many years.

The woolly adelgid spread quickly in the eastern hemlock southern range and extreme infestations have killed hemlocks throughout the Appalachian Mountains. It first made an appearance in Connecticut in the late 1980s, and some have speculated it was, literally, blown into the region by Hurricane Gloria in 1985.

Woolly adelgid is certainly a concern here in The Last Green Valley. Old Furnace State Park in Killingly bears the scars of this invasive insect. The park has large stands of ancient, eastern hemlock trees and many of them are now dead, skeletal hulks. On recent hikes to the park, I was pleased to see young hemlocks growing beneath their deceased ancestors, though their future is uncertain at best.

Extensive research is underway to find methods to mitigate the onslaught of the infestation, including biological control by introducing a species of beetle that is a natural predator of the woolly adelgid. The results have shown promise and are detailed in an August 2020 CT Examiner article by Cate Hewett. The article is linked below, and I suggest folks interested in the long-term health of our eastern hemlock take a look.


Another excellent source of information on the eastern hemlock is “Hemlock: A Forest Giant on the Edge,” edited by David Foster of Harvard Forest in Petersham, Massachusetts. The book examines the importance of eastern hemlock in the eastern United States and the changes to our hemlock forests during the last 5,000 years. For several years scientists at Harvard Forest have been undertaking field work and research into the eastern hemlock within the large stands of hemlocks located there.

Mother Nature also provides another important deterrent of the wooly adelgid. Severe cold, with several days of below zero temperatures, is effective in killing the insect. Throughout New England, this January has produced some very cold days and below zero windchill. Hopefully, this will aid in slowing the current advance of this invasive insect, at least in the more northerly range of hemlock trees.

Our region is dominated by deciduous trees, and we have fewer numbers of conifer species than colder northern regions. It would be a tragedy to lose one of our most beautiful conifer varieties, and hopefully a long-term solution to the woolly adelgid can be found before it is too late.

When walking the woods and along the streams and rivers in The Last Green Valley, look for the eastern hemlock. Enjoy its beauty, and take in the wonder of this amazing tree. Peek below the lower branches and perhaps you’ll find signs a deer or other animal has bedded down for the night. Hopefully, we’ll enjoy these beautiful trees for many years to come.

We live in a beautiful place called The Last Green Valley National Heritage Corridor. I invite you to learn more about our region’s natural and cultural resources and to join us in caring for them, enjoying them and passing them on to the next generation.

Bill Reid is the Chief Ranger of The Last Green Valley National Heritage Corridor and can be reached at 860-774-3300 or bill@tlgv.org


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