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Can Endangered Eastern and Carolina Hemlocks Be Saved?

The Eastern Hemlock is called the "Redwood of the East."

The Eastern Hemlock is called the "Redwood of the East."

Eastern and Carolina Hemlocks

The beautiful and stately eastern hemlock and Carolina hemlock are conifers that grace the forests from Nova Scotia in the north to Alabama in the south, and westward into parts of Michigan, Minnesota and Wisconsin. Carolina hemlock is a closely related species that grows in the southeastern U.S.

Providing food and shelter for wildlife, hemlocks help to moderate temperatures and cool the forest floor. They play a major role in preventing soil erosion along riverside banks. Their evergreen beauty makes them a popular choice for planting on private property. Called the "redwoods of the east," hemlocks are slow-growing and long-lived . They can grow as tall as 100 feet and live up to 400 years. But in a large area of the eastern U.S. they are endangered species.

Hemlock Woolly Adelgid


Eastern and Carolina hemlocks are being attacked by an insect that is not native to the region. In the 1950s the adelgid made its way into the eastern U.S. from Asia. The insect first appeared in the Richmond, Virginia/Washington D.C. area. Since then an estimated 50 percent of hemlocks in 11 states have been infected. The tiny insect, about 1/16th of an inch long, is identified by the white woolly tufts it creates on the hemlock's needles. It is known as the hemlock woolly adelgid, or HWA.

The adelgid reproduces asexually and can lay up to 300 eggs for two generations of new insects per year. Not only do adelgids multiply profusely they spread easily. They are so tiny they can be blown by the wind or become "hitch hikers" carried by birds and other animals.

Effects of Woolly Adelgid on Hemlocks

The HWA attacks the hemlock by sucking the sap from the needles. The hemlock needles are actually the trees' leaves where photosynthesis takes place and nutrients are made. At the same time the insect releases a toxin that the leaves absorb. The result is loss of needles, meaning poor nutrition for the tree. Thinning foliage will be noticeable in the crown of the tree. From a distance the tree will no longer appear lush green but rather a dull gray in color. Infected trees not treated will die within four to ten years.

After its accidental arrival on the North American continent the HWA spread westward towards the Blue Ridge mountains. Because the damage the HWA inflicts is so slow, the damage was not discovered for a decade or more. Slowly the damage was noticed and efforts began to treat the hemlocks and stop the spread of HWA.

Areas Most Affected by Woolly Adelgid

A 2009 study found that the HWA was spreading faster than expected in the southern Appalachian area, probably because of air pollution and climate. This same area was hit especially hard by the great chestnut tree blight of the early 1900s which significantly changed the forest composition of the area. The area is still rich with beautiful national parks and forests. It is urgent that the hemlocks be saved.

Located just 75 miles from Washington, D.C., Shenandoah National Park is 200,000 acres of recreational beauty in Virginia. Cascading waterfalls and beautiful vistas give park visitors a serene experience.

The HWA was discovered here in 1988. The hemlocks began dying two years later.

The Great Smoky Mountains National Park is located at the border of North Carolina and Tennessee. It is America's most-visited national park. Wildlife is abundant and diverse here, with 522,419 acres being almost 95 percent forest. The HWA attack here was first noticed in 2002.

The Chattahoochee-Oconee National Forest includes 865,855 acres spread across the South Carolina-Georgia border. Named for the Cherokee and Creek Native Americans, it encompasses parks, lakes, and hiking trails linking to the great Appalachian Trail. It is the home of the Chattahoochee River in the north Georgia mountains where the movie Deliverance was filmed. HWA was first detected here in 2002. It is estimated that 60 percent of hemlocks are infected.

Efforts To Save Hemlocks

Beautiful lakes, trails rivers and trees are plentiful in the southeastern national forests and parks.

Beautiful lakes, trails rivers and trees are plentiful in the southeastern national forests and parks.

The accidental arrival of the Asian insect decades ago, with its easy spread and slow-to-note effects is unfortunate. However, state and local agencies, the National Park Services, and the USDA's Forest Service are fighting the insect aggressively. Scientists at universities and research centers have joined the fight.

In the beginning the fight was slow. Selected trees in the Shenandoah National Park received a chemical treatment but funds were limited and access to so many trees was difficult. A good technique for treating the trees was needed.

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In the year 2000, ten years after HWA was discovered in central Pennsylvania, arborists used a hydraulic sprayer to mix chemicals and make medicine to inject into the ground for the roots of the trees to drink.

In 2006 arborists in the Great Smoky Mountains National Park treated 40,000 trees at $20 each. However, the treatment only lasted for three years.

Chemical "warfare" turned out to be impractical for these large forests. Even after being cured, infected trees could reinfect the treated ones. Scientists and arborists began to turn to biological methods to control HWA. Just as ladybug beetles eat aphids in our gardens, Asian beetles are natural predators for the adelgid insect. Progress with this biological method was important for treating these large forests. By 2004, one type of Asian beetle used caused a reported 87 percent reduction in infected trees in five months in Virginia and Connecticut.

Researchers continue to study biological control methods using natural predators including insects and fungi. Some scientists have studied the Asian hemlock's natural resistance to the insect and are successfully hybridizing those trees with the Eastern and Carolina species.

Research must continue to control this difficult problem to eradicate HWA and save our beautiful majestic hemlock trees in the eastern United States.

Treating Trees On Private Property

It is practical to use chemical and physical treatments against adelgids on Individual hemlocks and small stands. Use these tips if you notice HWA on your hemlocks.

  • use chemicals from a licensed arborist
  • physically remove adelgids by washing with insecticide soap
  • cut off infected branches
  • remove any bird feeders from near trees
  • make sure any neighbors' trees are checked and treated
  • contact your local USDA extension office for further advice

Help Raise Funds For Research

The Hemlockfest Music Festival is held annually the first full weekend in November in Dahlonega, Georgia. The festival is held to raise funds to support Georgia research labs and increase awareness of HWA. Enjoy great music, primitive camping, canoeing, exhibitions, local arts and crafts, food and drink vendors, and more. Dahlonega is only an hour's drive north of Atlanta. Y'all come on down and have a great time for a good cause. If you can't, please look for similar fundraising efforts in your area.

A Humorous Video To Describe A Serious Problem


Rebecca Mealey (author) from Northeastern Georgia, USA on April 25, 2015:

Thanks Pawpaw...and happy Arbor day.

Jim from Kansas on April 25, 2015:

Always sad when an invasive species does so much damage. I hope there is a final solution with time. It always makes me nervous when they use one non native species to fight another. Hope it all works out.

Jackie Lynnley from the beautiful south on August 31, 2014:

Read this before but worth another share to remind people about this important tree. I noticed yesterday along interstate they are cutting masses of trees in different locations some of which could be Hemlock. They are not in a place to bother anything or enough room for businesses. I think some people with saws get a trigger happy finger!

Rebecca Mealey (author) from Northeastern Georgia, USA on December 24, 2012:

thanks for taking the time to learn of their plight!

moonlake from America on December 24, 2012:

We had hemlocks at our other home but not here. I never knew they were in trouble. Thanks for the informationg. Voted up . Merry Christmas.

Rebecca Mealey (author) from Northeastern Georgia, USA on December 24, 2012:

Merry Christmas to you! Come down to Dahlongna Georgia next year for the Hemlock Fest!

ahorseback on December 24, 2012:

rebecca , Awesome hub ! Here in Vermont as well the hemlock is suffering , They are releasing a couple of different bettles or some kind of bug !lol even now ! hey , Merry christmas !

Rebecca Mealey (author) from Northeastern Georgia, USA on April 27, 2012:

Thanks for commenting whonunuwho! Hemlocks are harvested for lumber a good bit in the north. That is a great point and one I missed. Around here thy are mostly ornamental, or grow in the wild. The hemlocks are endangered all over the east,and are not the only endangered species I am sure. You are so right. Carelessness and greed...goodness, you almost wrote a Hub in this comment. Thanks again!

Rebecca Mealey (author) from Northeastern Georgia, USA on April 27, 2012:

Thanks ChristyWrites! I am so glad to be spreading the word. Endangered trees are a serious matter!

whonunuwho from United States on April 27, 2012:

Deforestation and the wanton disregard of our natural forests, has reached an all time high.It is causing loss of life of many species all around the world in flora and fauna. The carelessness and greed of lumber companies and little policing of the laws and activities that go on, results in the loss of not only our beautiful forests, but in the long run, is a national committing of suicide.We must keep our trees that produce the air that we breathe and the habitat for thousands of wildlife in order to prolong the food chain that is vital to our world's survival. Wonderful hub.

Christy Birmingham from British Columbia, Canada on April 27, 2012:

I am glad you are spreading the word about this issue. The maps are a great touch in the hub to help your information seem even more pertinent. I vote up!

RTalloni on April 26, 2012:

Our hemlock is such a beautiful tree. Thanks for highlighting this concern. Maybe we'll get to check out the festival this year!

Rebecca Mealey (author) from Northeastern Georgia, USA on April 23, 2012:

Thanks Alastar. Research in recent years is sounding better for the Eastern hemlock. It started out not so good!

Alastar Packer from North Carolina on April 23, 2012:

These "Redwoods of the east" are magnificent trees, they really are. Excellent article on them rebecca. Lets hope all the efforts will be more successful in stopping those destructive algenids.

Rebecca Mealey (author) from Northeastern Georgia, USA on April 22, 2012:

Thanks for stopping by, prasetio30. The hemlock is a beautiful tree!

prasetio30 from malang-indonesia on April 22, 2012:

I had never seen the hemlocks in person. Thanks to introduce this tree with us. Rated up and useful. Take care!

Love and peace,

Rebecca Mealey (author) from Northeastern Georgia, USA on April 21, 2012:

Thanks Jackie for your concern over this nasty insect that is killing our precious trees!

Jackie Lynnley from the beautiful south on April 21, 2012:

So many things like this happening because of man. The last two days while working outside I can't get over all the bugs and things, just so very many. I am not afraid of anything really though I hate the super-glue slugs it is just so noticeably multiplying and about anything in the dirt or on top is after your plants. Thanks for informing us about this, and I do hope someone will act quickly enough. Very interesting and useful.

Rebecca Mealey (author) from Northeastern Georgia, USA on April 21, 2012:

Thanks teaches12345. It is really serious, I hope they get the problem under control. I'm glad you watched the video. It cracked me up when it went from serious to people dressed up like the thing!

Dianna Mendez on April 21, 2012:

I hope the HWA is controlled before we lose so much of our forest area. I remember when the worms attacked the chestnut trees in Virginia. They ate through the trees rapidly. The video is humerous, but has its serious points as well -- love the giant bugs!

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