But, they are dying forests. The culprit is a tiny non-native insect, the balsam woolly adelgid. Sixty percent of the remaining Fraser firs in the national park are infested. The adelgid begins to affect firs about the time the young trees begin to produce cones and the bark begins to roughen. As many as 50,000 insects may infest a single tree.
Adelgids can kill a fir tree in as little as three years.
Heavily infested trees look as if they have been whitewashed. When an adelgid finds a suitable feeding site it inserts its mouthparts into the bark and remains attached for the rest of its life. The adelgid injects a toxin into the tree as it feeds on the sap. This toxin disrupts the flow of water and nutrients. The balsam wooly adelgid was introduced into New England around 1900 on nursery stock.