In Miller's Grove,
Massachusetts, an exterminator inspects the basement of Dr. Jeff Eckerle, having been hired to eradicate a
cockroach infestation. As the exterminator attempts to crush a roach underfoot, he collapses from
anaphylaxis while the roach crawls out from under his boot, unscathed. When Eckerle returns, he finds the exterminator's body covered with roaches.
Fox Mulder (
David Duchovny) is coincidentally nearby, investigating reported
UFO sightings in Miller's Grove. While on the phone with
Dana Scully (
Gillian Anderson), he is approached by the local sheriff, Frass, who reveals that a series of "roach attacks" have taken place in the town. Frass allows Mulder onto the scene at Eckerle's residence. Elsewhere, a trio of teenagers huff
fumes generated from heated manure. One of them sees a roach crawl into an open wound on his wrist. In an attempt to extricate the insect, he begins to frantically slice his skin with a razor, leading him to sever an artery and 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 roach on the underside of a piece of furniture, indicating that roaches were at least present. When he attempts to capture the roach for analysis, it 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. Frass purports that the government, under the guise of the
USDA, has been breeding killer roaches in a nearby facility. Immediately afterwards, the
medical examiner is found dead in a bathroom stall, initially covered with roaches 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 Frass find a seemingly dead roach on a sink in the bathroom, and Mulder again attempts to capture it, but it proves to be alive and escapes down the drain. Mulder investigates the facility Frass mentioned. Before breaking in, he and Scully discuss the odd behavior of the roaches, with Scully hypothesizing that they 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 USDA who is studying roaches 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 visit Miller's Grove herself. Mulder brings a roach from the hotel room to Berenbaum, who thinks it may be mechanical. He then visits Dr. Ivanov, a wheelchair-using scientist who works on insect-like robots. The two discuss the possibility that extraterrestrial intelligences could send robotic probes to study other planets. After inspecting Mulder's specimen, Ivanov is rendered speechless; he informs Mulder that the specimen is, technology-wise, vastly superior to anything he's ever seen. Scully arrives in the town at a convenience store, finding the residents succumbing to
mass hysteria over the roaches. She attempts to calm the people down, but they instead frantically flee after two scuffling patrons knock over a display of chocolate candies, believing them to be more roaches. Mulder catches another roach to bring to Berenbaum, but this time she concludes that it is a seemingly normal insect. Scully finds out that Eckerle was researching dung-derived
methane as an alternative fuel source, and had been importing animal dung that may have introduced the roaches to the area. Upon hearing this, Mulder speculates that the roaches are actually extraterrestrial robotic probes that are capable of consuming dung—an abundant resource already exploited by some species of roaches—to generate methane as a source of fuel. Mulder goes with Berenbaum to see Eckerle at his facility. She stays in the car while he goes inside, finding Eckerle in a deeply paranoid state. Eckerle pulls a gun on Mulder, thinking that even he may somehow be a cockroach. Scully arrives on the scene and meets Berenbaum. She then goes in the facility looking for Mulder and then phones him; when his phone rings, Eckerle believes it to be Mulder making a tone like the rest of the unusual roaches. He fires at Mulder, and his shots rupture and ignite pipes containing methane gas. The agents flee, and the facility explodes with Eckerle still inside. The next day, Ivanov arrives at the scene to talk with Mulder and meets Berenbaum. The two leave with one another, discussing their interests in insects and robots. That night Mulder writes his report on the case, wondering how humanity would react if insect-like robots visited Earth. Mulder finds a
Blaberus giganteus by his food and crushes it with an
X-File. == Production ==