Wooly adelgid infestation could lead to end of hemlocks here

An invasive pest is threatening to destroy a native tree species here and few options have been given to save it.

"The hemlock trees could go the way of the American Chestnut," said David Isner, agent with the Alleghany Cooperative Extension Office. The wooly adelgid, a small insect which originally came here from China, has been spotted from Doughton Park in the southern part of Alleghany to the New River in the northern part of the county.

"It can basically be found everywhere in the county already and has been here for some time," said Isner.

While the adelgid, a nearly microscopic insect that attacks hemlock trees exclusively, is not immediately fatal to the trees, it is always fatal in the long term. No eastern hemlocks or Carolina hemlocks have proven resistant to the pest.

The adelgid's method of operation includes sucking the sap from the trees and then laying eggs, or cocoons, on branches where its young later feeds. It is typically spread by birds, which get the sticky cocoons on their feet and go from one tree to another. Ironically, while those birds do help spread the pest, they are among the animals that could be affected by the demise of the tree, since they depend on the hemlock for nesting sites and food.

Adelgids reproduce at a rapid pace and are parthenogenic, meaning that all individuals are female and don't need males to reproduce. With its potential for rapid growth, one adelgid can kill a mature hemlock in as little as four years if the tree is stressed by drought.

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