At what level does caterpie evolve?

Caterpie evolves into Metapod starting at level 7, and then Metapod evolves into Butterfree starting at level 10.

Caterpie is #10 in the National Pokedex, and was introduced in the Generation I Pokemon titles (Red, Blue, and Yellow) where it could be found in Viridian Forest, in Red and Blue on Route 25 and in Blue only on Routes 2 and 24. In Generation VI (X and Y), it can be caught in Santalune Forest, and in Y only, on Route 2.

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Of course if you want it to learn more moves, it never hurts to not allow it to evolve for a bit!