Its cloak is based on what location it most recently battled in. If it battled in a grassy area, it will have the grass cloak. If it battled at a beach or in a cave, it will have the sandy cloak. If it fought in a building, it will have the trash cloak. Once a (female) Burmy evolves into Wormadam, its cloak becomes part of its skin, and decides the Wormadam's second type.