Moore.
Larry Moore is an employee of the Federal Forest Service. He assists Mulder and Scully with the investigation of the disappearance of thirty loggers in the Olympic National Forest area.
According to Moore, Federal Forest Service employees are referred to as Freddies by eco-terrorsists. While talking to Mulder and Scully about the investigation, we learn that Moore is just as concerned about the forest and the environment and has "no quarrel with the eco-terrorists in principle," but does have a problem with their "methods."
Through a core sample of an illegally cut 500 year old, Douglas Fir tree, Moore discovers a "tiny bug" living in the oldest and most deep part of the tree. He explains to Scully and Mulder that when parasites attack trees, it is the living part of the tree they attack, such as the leaves, roots, and new-growth rings. Moore is baffled and suggests it might be a wood mite, but he can't make sense of the wood mite's ability to live in the center ring, which is the dead part of the tree, as wood mites need water to survive.
Moore, along with Scully and Mulder, is quarantined and treated at a high containment facility in Winthrop, Washington after being attacked and cocooned by a swarm of wood mites. (TXF: "Darkness Falls")