Director: Kim Manners
When an archaeological expedition from the Boston Museum of Natural History excavating a site in Ecuador uncovers an Amaru Urn, containing the remains of a female shaman, which the Secona Indians believe is sacred to their tribe. The head of the expedition Dr. Roosevelt orders the urn be shipped back to the US despite warnings from the Indian liaison for the expedition Dr. Bilac that the urn should be left undisturbed. That removing the shaman's remains would be against the wishes of the local tribe people.
Dr. Roosevelt dismisses his warning and is later attacked and killed by a wild cat. No sooner has the urn arrived in Boston then one of the archaeologist is found dead in the museum. Mulder and Scully are called in to investigate, the museum's curator Dr. Lewton believes that the murder is politically motivated as the Ecuadorian's have lodged a complaint with the State Department. Mulder tells Scully that the Ecuadorians believe anyone who disturbs a Amaru urn will be cursed. Mulder and Scully's investigation centres on Dr. Bilac, who since his return from the expedition has become a recluse.
He claims that the killings are down to a jaguar spirit sent by the Secona Indians. But Scully suspects his involvement given that he is heading up the campaign to return the shaman's remains to Ecuador. As more members of the museum befall the same fate as their colleagues, Mulder and Scully try to determine if it is all the work of an ancient curse or political terrorism.
Gillian Anderson is very allergic to cats, so makeup effects artist Toby Lindala had to create a cat puppet with rabbit fur that attacks Scully.
After the episode aired, the network found out that 'bichos' also means 'balls' in Columbia and Venezuela. John Shiban, the writer, didn't know that when he wrote the episode.
Director Kim Manners awarded the crew with 'Teso Dos Bichos Survivor' t-shirts with the words 'Second Salmon' after production was completed. 'Second Salmon' refers to the script, which changes color with each revision. In this case, the script underwent so many changes that they ended up with a salmon-colored version twice.
When Mulder and Scully begin to crawl into the tunnel under the museum, Mulder's famous line 'Ladies first' wasn't in the original script.
As well as the name of the area where the Urn was discovered, "Teso" is Portuguese for "burial ground" and "Bichos" means "small animals".
Scully: So, what are we talking here, Mulder, a possessed rat? The return of Ben?
Mulder: No, I think those rats were killed trying to escape from something.
Scully: From something that sent them diving into the toilet.
Mulder: No, the lids were down. They weren’t trying to get into the toilets, they were trying to get out. They were coming from within the sewer lines trying to get away from something.
Scully: Have you been drinking Yaje, Mulder?
Mulder: Go with it, Scully.