Wurmple is one of those well known bug Pokémon that is more renown for its fast evolutions than its battle efficiency. Unlike other Pokémon, Wurmple has a branching evolution line that can lead it to become either a Beautifly or a Dustox. Here is how to evolve it to either in Pokémon Legends: Arceus.
Unfortunately, if you are looking to specifically get a Beautifly or Dustox through evolution, there is no guaranteed way to make Wurmple take that evolution path. Luckily, though, the process should be really quick to find which way it will go.
Wurmple can first evolve at level 7. When it hits that point, select them in your pack and have them evolve. Depending on their personality, which is randomized, they will evolve into either Silcoon or Cascoon. After that, take them to level 10 and Silcoon can evolve into Beautifly and Cascoon into Dustox.
Wurmples can be easily found in the beginning of the game and are very easy to catch with normal Pokéballs. For your best chances to get both evolutions, have a couple Wurmples in your party and just never send them out to battle. Have the rest of your party win battles and the Wurmples will get to level 7 quickly and you can see which direction they are going. If it doesn’t end up going the way you want, grab another Wurmple and try again.