HARRISBURG, Pa., April 8, 2013 /PRNewswire-USNewswire/ -- A non-native, invasive insect that attacks and kills Eastern hemlock trees has advanced westward across Pennsylvania to Clarion and Jefferson counties where infestations have been confirmed in two state parks. "The hemlock woolly adelgid, a pervasive insect threat that has killed thousands of hemlocks across the state, has been detected in both Cook Forest State Park, Clarion County, and Clear Creek State Park in neighboring Jefferson County," Department of Conservation and Natural Resources Secretary Richard Allan said. "This discovery is especially unsettling due to the signature hemlocks in both parks' forests." Home to the most significant Eastern hemlock stand north of the Smoky Mountains, Cook Forest State Park is famous for its old-growth trees. Its "Forest Cathedral" of towering hemlock and white pine is a National Natural Landmark. For this reason, and in the face of the insect's steady, northwestward spread, DCNR entomologists, foresters and park officials had ramped up early-detection efforts at the two parks. Attempts to delineate wooly adelgid infestation and chart feasible methods to combat its spread are now under way, Allan said. "Park staff members have been regularly monitoring for the pest, and those surveys paid off with early detection that will allow for greater treatment options and better success," Allan said. "Weather and snow cover have hampered attempts to gauge the insect's spread, but we know there is infestation along the Clarion River, which flows through both Cook Forest and Clear Creek state parks." DCNR will be embarking on a two-pronged treatment effort that relies on selective application of insecticides and the release of predatory beetles.