In May 2002, the first incidence of woolly adelgids on hemlocks in the Great Smoky Mountains National Park was reported. Adelgids are natives of eastern Asia and were found in the western United States in 1924. They are fatal to hemlocks. Currently, half of the tree's eastern range is infected. Peeples discusses how the loss of hemlocks would impact on the environment of streams and wildlife and what biologists are doing to eradicate the pests. One approach is to introduce an adelgid predator from eastern Asia, though this is not without its own possible consequences.