The Surprising Cause Behind the Dead Trees in the Smoky Mountains

It's not forest fires or falling leaves, it's an invasive bug

There’s a war going on in the Great Smoky Mountains. On one side is an army of invaders disturbing the native flora and leaving an array of sick trees in their wake. These menacing creatures in the Smoky Mountains are the hemlock wooly adelgids, an insect native to East Asia. On the other side of this war is the National Park Service (NPS), which has banded together with an army of predatory beetles.

They are the reason you see so many bare trees in the Great Smoky Mountains National Park. The insects leave tall, decaying trees standing out in stark contrast to the forests’ thick green canopy. The species has been destroying Fraser firs on Mount Mitchell in North Carolina as far back as 1957.

Dead trees in the Great Smoky Mountains are due to an invader called hemlock wooly adelgids. The infestations appear like small cotton balls on the base of the tree's needles. These invaders deprive the tree of its proper nutrients, starving the tree within three to five years. The National Park Service has introduced predatory beetles to eat the invasive adelgids. You can help by supporting non-profits who fight to protect the trees in the national park.

IN THIS ARTICLE

• What do Adelgids look like and how do they feed?
• The Park Service fights bugs with bugs
• How the general public can help

By the 80s, the situation was deemed apocalyptic. There were fears the Fraser firs would suffer the same fate as the American chestnut, which nearly succumbed to a fungus accidentally introduced to the region in the 40s. However, with park officials taking steps to counter the adelgid and the forest itself developing genetic resistance, the Fraser fir is making a comeback.

Called the "redwood of the east," eastern hemlocks can grow more than 150 feet tall on trunks measuring six feet in diameter. Some hemlocks in the park are over 500 years old, according to the NPS. Originally discovered in 2002, adelgid infestations have now spread throughout the park's hemlock forests. As a result, many infested trees are now gone.

What do Adelgids look like and how do they feed?

Adelgid infestations are easy to spot by the appearance of tiny "cotton balls" at the base of hemlock needles. This appearance is also more visible from fall through spring according to the NPS.

“The hemlock woolly adelgid feeds on the sap at the base of hemlock needles, disrupting nutrient flow and causing the needles to change from deep green to a grayish green, and then fall off," says the NPS.

"Without needles to capture sunlight (the process of photosynthesis) the tree starves to death, usually within three to five years of the initial attack."

- The National Park Service

The hemlock wooly adelgid exists in Eastern Asia and also the Western United States. However, the combination of natural predators and host resistance limits the damage done by the bug in both places.

The Park Service fights bugs with bugs

I would very much like to make some Beatles puns here, but the case facts are far too interesting to be mucking about. In 2002, park officials unleashed an army of predatory beetles on the forest. These little beetles feed exclusively on adelgids. Ha, take that you sap suckers. By 2011, the park had unleashed over half a million beetles. Preliminary indications are that the results are encouraging. In fact, you might say "I’ve Got a Feeling" that everything is going to "Come Together" and the situation is "Getting Better".

Other steps of action include various pest treatments. Hemlocks that are in accessible areas are treated with insecticidal soaps and horticultural oils. Truck-mounted spray units distribute these treatments with an 80-foot reach. Of course, off-trail hemlocks that can’t be reached by the insecticidal super soaker have their soil treated. Alternatively, they can have insecticide injected directly into the trunk.

How the general public can help

Efforts to control hemlock woolly adelgids are being funded through the Save the Hemlocks initiative of the Friends of Great Smoky Mountains National Park, a nonprofit organization. For additional information, or to learn more about how you can help, visit the Friends of the Great Smoky Mountains National Park's website or call (865) 932-4794.

Did you know that's why there were so many dead trees in the Smokies? Let us know in the comments.