"This particular lichen is called letharia vulpina-- 'wolf lichen.' They'd put out pieces of meat with crushed glass and bits of the lichen in it. The glass perforated the intestines of the animal so the vulpinic acid could reach the internal organs faster."
"What did you do to my wolf?"
"Well, I didn't poison him with lichen... But I did give him a powerful paralytic agent. The same one I put on that jar."
"I guess we both know a few things, Ikeda-san. Born out of the blood of a Nogitsune, this lichen is quite special. More powerful than you know."
"What-what are you going to use it for?"
"There's a Fox hiding inside a teenage boy... and I'm going to poison it."
Alan Deaton and Ikeda about letharia vulpina

Letharia Vulpina is the nineteenth episode of Season 3 and the forty-third episode of Teen Wolf.


Scott and the others try to prevent a disaster. Lydia and Allison seek out an unlikely teacher.


Deaton retrieves a poisonous plant that will aid him in defeating the Nogitsune. Derek and Chris Argent are arrested by Agent McCall for the murder of Katashi after being framed by someone. Stiles, who is still missing, reappears in the school basement. After finding a map of the cross-country trails, he, Scott, Aiden and Ethan realize that the path has been booby-trapped by Stiles. The boys are successful in stopping the runners from being injured but Coach Finstock is shot with an arrow. Allison and Lydia seek the aid of Peter Hale. He asks for Lydia's help in finding the memory that his sister took away from him. Lydia discovers that Peter is a father. The Oni, attack Stiles, Scott and Kira at the animal clinic. They manage to escape but Stiles-- still possessed by the Nogitsune-- knocks Kira unconscious and tortures Scott with an Oni ninjato until Deaton returned and suppressed the Nogitsune's influence on Stiles with letharia vulpina.


Main Cast

Supporting Cast

Guest Cast



  • The title refers to a specific strain of lichen, or moss, known as letharia vulpina, or "wolf lichen." It is commonly used as a poison by mixing the lichen with raw meat and pieces of broken glass to cause the vulpinic acid to enter the bloodstream of the fox, coyote, or wolf who eats it and kills them. The specific letharia vulpina that is found by Alan Deaton in Ikeda's garden was born from the blood of the Nogitsune who possessed Ikeda's father, the Kumicho of the Japanese Yakuza clan who had an arms deal with Chris Argent in the late 1980s, making it powerful enough to use to temporarily weaken the Nogitsune possessing Stiles Stilinski.
  • The Nogitsune demonstrates that he has the ability to absorb pain, just like Werewolves can, only to a much more powerful degree, which confirms what Katashi and the Nogitsune have said about Void Kitsune feeding on chaos, strife, and pain. The Nogitsune used this ability to siphon all of the pain that Scott had absorbed throughout the day from Isaac, Coach Finstock, and a dying deputy who was injured in the explosion at the Sheriff's station.
  • In this episode it is revealed that Malia Tate is the biological daughter of Peter Hale, Lydia discovered this information after using her Banshee abilities to listen to the memory inside Talia Hale's claws

Body Count



  • "Hold On" by William Fitzsimmons
    • Scott and Melissa discuss Stiles before making plans to visit Isaac in the hospital. Sheriff Stilinski gets a text from Stiles telling him not to look for him.
  • "Renegade (Radio Edit)" by DANK
    • During cross-country practice, Kira realizes that one of her Kitsune abilities is super-speed and is amazed when she easily laps Danny, who is the fastest human runner on the team.
  • "Dreaming of You (Svenson & Gielen Remix)" by Thrillseekers
    • Ethan tackles Danny in the preserve and makes out with him. Kira runs so fast that Scott has to leap in the air and spin them both around just to stop her.
  • "2 Thingz" by Basecamp
    • Lydia and Allison go to Derek's loft to get help from Peter regarding Lydia's Banshee abilities
  • "Apple Pie" by Cameron the Public
    • After being shot with an arrow at cross-country practice, Coach panics and tells Stiles, Scott, and Ethan to pull out the arrow in his stomach