Spewpa has a small cotton on its body, which can emit sprinkles.
Spewpa gains a stiff carapace once it evolves from Scatterbug, so less forceful attacks will hardly make a scratch.
Spewpa is the first cacoon Pokémon that is the same size as its pre-evolution, Scatterbug.
Spewpa is most likely derived from the word "spew" and "pupa". The "spew" references the "spewing" of insects, and "pupa" because it is in a shell-like form, as well as being evolved from Scatterbug and the pre-evolution of Vivillon.