beer and huff fumes generated from heated manure. One of them sees a roach crawl into an open wound on his wrist, and in an attempt to extricate the insect, he begins to frantically slice his skin with a razor, leading him to sever an artery and ultimately bleed to death. At the scene, Mulder talks over the phone with Scully, who explains that it is likely a case of drug-induced delusional parasitosis, though Mulder finds a cockroach on the underside of a piece of furniture, indicating that roaches were at least present. When he attempts to capture it for analysis, the insect crumbles in his hand and the sharp pieces cut his fingers in the process, leading him to believe that the brittle casing was made of metal. Sheriff Frass purports that the government, under the guise of the USDA, has been breeding killer cockroaches in a nearby facility. Immediately afterwards, the medical examiner is found dead in a bathroom stall, initially covered with cockroaches that disappear from the scene before more than one person can witness them. Scully attributes the medical examiner's death to a cerebral aneurysm induced by overstraining while defecating. Mulder and Sheriff Frass find a seemingly dead cockroach on a sink in the bathroom, and Mulder again attempts to capture it (albeit more gingerly this time), but it proves to be alive and escapes down the drain. Mulder goes to investigate the facility Sheriff Frass mentioned. Before breaking in, he and Scully discuss the odd behavior of the roaches, with Scully hypothesizing that the roaches could be an invasive species. Inside the facility, which resembles a typical house, Mulder sees the walls rippling and is quickly surrounded by roaches. He is then confronted by Dr. Bambi Berenbaum (Bobbie Phillips), a researcher from the Department of Agriculture who is studying cockroaches to develop more effective methods of pest control. Berenbaum has great interest in insects and, incidentally, believes that some UFOs are actually insect swarms flying through electrically charged airspaces. Yet another death occurs in Mulder's hotel, with the individual being found covered in roaches that quickly flee. At this point, Mulder believes that the individual simply died of fright, though Scully begins to wonder what is going on and decides to head up there herself. Mulder brings a cockroach from the hotel room to Berenbaum, who thinks it may be mechanical. Mulder then visits the