"The Host" is the second episode of the second season of the science fiction television series The X-Files, premiering on the Fox network on September 23, 1994.

The show centers on FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files.

Carter claimed to have been inspired to write the episode based on three incidents; his dog having worms, his research into Chernobyl, and the extinction of species during the 1990s.

Mulder believes it is simply a case of gang-related murder, and angrily confronts Assistant Director Walter Skinner, feeling he has been given this "wild goose chase" as a form of punishment.

Scully performs the autopsy on the crewman's body, finding a Russian language tattoo on his arm and a flukeworm inside his liver.

Mulder visits a sewage processing plant and, along with a foreman named Ray, finds a large humanoid mutant with a fluke-like mouth.

Mulder insists that Craig's death could have been prevented if the X-files had remained open, but Skinner implies that the decision came from higher up the chain of command.

In addition, the story expanded upon the Flukeman's backstory, revealing that he was a liquidator named Gregory, who, after being locked in a sewage tanker truck at Chernobyl, gestated the mutated flukeworm that grew into the original Flukeman after he was exposed to irradiated cooling water from the still-burning nuclear reactor and to flatworms in the sewage tank.

"[7] Producer J. P. Finn described the episode as a departure from Carter's usual work as it did not deal with an alien subject matter.

[8] The Flukeman suit used by Morgan, which included flipper-like feet, yellow contact lenses and fake teeth,[9] took six hours to put on; this process was eventually sped up.

[11] Carter described the character as "the embodiment of everyone's sense of vulnerability, the idea of something that exists in the underworld of the sewer system and might in fact come to bite you in the least elegant of places".

[11] The sewer scenes were shot in a pit on the show's stage,[6][7] with Carter using his father, who worked as a construction worker, as a consultant on how to build it.

[6][12] As no ship was available for filming the opening scenes in the Russian freighter, a hydro sub station in Surrey, British Columbia, was adapted into an engine room.

Entertainment Weekly gave "The Host" a rare A+, noting that it was "a refreshing instance of a fully and satisfactorily resolved episode — like a perfect meal, although you definitely don't want to eat during this one.

Club described the episode as "the first really, really icky X-Files", and while considering redundant the "circular" nature of the plot, with the creature coming back to the sewers after escaping, he felt that "The Host" "holds up because of the Flukeman's irreconcilable ugliness, and because it continues down the path that "Little Green Men" started on".

Club's Zack Handlen described the flukeman as a "beyond icky" monster that "just looks wrong", adding that "the plain fact of its existence is horrifying enough that it doesn't need to do more".

[17] Connie Ogle from PopMatters ranked the character among the "best" monsters-of-the-week, describing it as "something of a poster boy for XF villains," and considering that "never has toxic waste seemed so dangerous as when the big slimy white fellow slithers onto the screen and starts attacking people in the sewers.