Detweiler Run Natural Area (Revisited) (21)
Hemlock woolly adelgid (Adelges tsugae), Huntingdon County, within the Detweiler Run Natural Area of Rothrock State Forest.
The hemlock woolly adelgid is an exotic insect pest that has wreaked havoc on forest and stream ecosystems across eastern North America. Small, white, cottony sacs at the base of the needles indicate the insects’ presence.
Most of Rothrock State Forest is infested, even at the highest elevations. The infestation is especially severe along the northern stretch of Bear Meadows Road; many trees there are dead or dying. In the Detweiler Run Natural Area, the trees along Detweiler Road and the pipeline swath are the most damaged. The trees near Detweiler Run (including the old-growth specimens) seem to be faring better.