Caterpie is a serpentine Pokémon that resembles the larvae of the Spicebush Swallowtail. It is a green caterpillar with yellow ring-shaped markings down the sides of its body, and large yellow eyes with black pupils. Its most notable characteristic is the bright red antennae (osmeterium) on its head, which releases a stench to repel predators. These and the large eye-shaped markings help to startle predators. Its feet are tipped with suction cups, permitting this Pokémon to scale most surfaces with minimal effort.
Caterpie will shed its skin many times before finally cocooning itself in thick silk. It can also spit this silk in order to entangle foes as seen in Ash Catches a Pokémon. It has a voracious appetite that causes it to eat leaves larger than itself. It primarily feeds on vegetation, such as tree leaves. According to Pokémon Adventures, its favorite food is the Vermilion flower. Caterpie lives in forests.
Caterpie is the second wild Pokémon that Ash captures in the manga. It was caught in Pikachu, I See You!. It evolves twice in Play Misty For Me - first into Metapod while Ash is showing off his Pokémon to Misty, and then into Butterfree during his Gym battle against Misty.
Ash is not shown releasing his Butterfree in the manga, although it is not seen after Haunting My Dreams.
Caterpie made its main appearance in the Yellow arc. With the help of her fishing rod and Red's Pika, Yellow saved a Caterpie from its tree, which was targeted by a fire attack. Caterpie then followed Yellow to where she and Blue were training, next to the Rock Tunnel. It took Yellow a whole day to properly catch this Caterpie with a Poké Ball, but once she prevailed, Yellow welcomed Caterpie to her team and called it "Kitty". It then became one of Yellow's most useful Pokémon, whose string was commonly used to make floaters. However, in the battle against Lance, Yellow did not have a Pokédex, which she needed to stop her Pokémon from evolving, and so Kitty evolved into Metapod and then into Butterfree right afterwards.
In the Pokémon Get da ze! manga
Shū has a Caterpie that he uses in various creative ways, mostly involving strange uses of its String Shot.
In the Pokémon Mystery Dungeon: Ginji's Rescue Team manga
Pokémon Mystery Dungeon: Caterpie is rescued in the first mission of the game. It is too young to be of any help to the rescue team but remains a strong fan throughout the game, even in its darkest hour.
Pokédex entries
This Pokémon was unavailable prior to Generation I.
Caterpie has a voracious appetite. It can devour leaves bigger than its body right before your eyes. From its antenna, this Pokémon releases a terrifically strong odor.
Due to this, it was impossible to complete a Generation I game using only Caterpie or Metapod, since Struggle couldn't hit Ghost-type at the time.
In the anime and in Pokémon Adventures, Caterpie holds the record as the Pokémon who takes the least time to evolve twice, taking only one episode in the anime and one chapter in Pokémon Adventures.
Origin
Caterpie is a stylized caterpillar, most resembling an Eastern Tiger Swallowtail caterpillar. Its "antenna" is an osmeterium, an organ unique to swallowtail caterpillars which, like Caterpie, they use to emit a foul odor. The tip of Caterpie's tail resembles the horn at the end of most species of Hawk moth larvae.