Eastern hemlock (Tsuga canadensis) regeneration in the presence of hemlock woolly adelgid (Adelges
tsugae) and elongate hemlock scale (Fiorinia externa) Can.
Evidence of a polymorphic life cycle in the hemlock woolly adelgid, Adelges
tsugae Annand (Homoptera: Adelgidae).
Over the past two decades, several exotic pests, such as the balsam woolly adelgid, Adelges
piceae (Rathzeburg), beech scale, Cryptococcus fagisuga Lind., elongate hemlock scale, Fiorinia externa Ferris, and hemlock woolly adelgid, Adelges
isugae (Annand), have become established in Tennessee and have the potential to dramatically change the composition of the fauna and flora within the area (Hughes, 1993; Lambdin et al., 2005; Vance, 1995).
Interest in hemlock, because it is increasing in abundance in many areas as forests mature and because it is being threatened by the hemlock woolly adelgid (Adelges
tsugae Annand.), resulted in two recent regional conferences on hemlock ecology and management (Mroz and Martin 1996, McManus et al.
Understanding the response of stands infested with hemlock woolly adelgid (HWA, Adelges
tsugae) is a critical step in identifying the influences this introduced insect will have on ecosystem processes and landscape dynamics.
In this case, a non-native insect, the balsam wooly adelgid (Adelges
picea), was accidentally introduced into the United States from Europe.
Fraser firs (Abies fraseri) infested by the aphid (Adelges
piceae) have been considerably reduced in numbers, especially in the southern region of the Appalachians.
For example, stands such as these are currently threatened by logging pressures, and the introduced hemlock wooly adelgid (Adelges
tsugae) (Orwig and Foster 1998).
1920s The hemlock woolly adelgid (Adelges
tsugae) is discovered on the West Coast.
Balsam woolly adelgid, Adelges
piceae (Ratzeburg) (Hemiptera: Adelgidae), an insect native to the fir forests of central Europe, was introduced to the United States around 1900 and is considered a pest of native North American true firs .
(Pinaceae) infested with Adelges
tsugae Annand (Hemiptera: Adelgidae) (Lu et al.
Responses of Acadian flycatchers (Empidonax virescens) to hemlock woolly adelgid (Adelges
tsugae) infestation in Appalachian riparian forests.
(1999) found that the abundance of galls of Adelges
abietis (L.) (Homoptera: Adelgidae) was higher on intermediate-sized trees and shoots of the white spruce Picea glauca (Moench) Voss (Pinaceae).
The exotic hemlock woolly adelgid, Adelges
tsugae (Annand) (HWA), currently threatens to destroy the hemlock forests throughout the eastern United States (McClure, 1997).
and Free.); and a galler, the spruce gall adelgid, Adelges