You've probably been there. You catch a Wurmple, feed it a mountain of Rare Candies or grind through the tall grass of Eterna Forest, and then—poof—it turns into a Silcoon. Again. If you're trying to figure out how to get Cascoon, you're likely realizing that Pokémon's most frustratingly random evolution isn't actually random at all. It’s just governed by math that the game refuses to show you.
Honestly, Cascoon is one of those Pokémon that collectors kind of dread. While its counterpart Silcoon leads to the elegant Beautifly, Cascoon is the gateway to Dustox, a Poison/Bug-type that has a weirdly loyal fan base despite its mediocre stats. But if you’re completing a living dex or just want that purple cocoon for your team, you need to understand the underlying "Personality Value" system.
The Secret Math Behind How to Get Cascoon
Most people think Cascoon is a 50/50 coin flip. It’s not.
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Every Pokémon has a hidden string of numbers attached to it the moment it's generated in the wild. This is called the Personality Value (PV). It's a 32-bit integer, which sounds like technical jargon because, well, it is. But for your Wurmple, this number is everything. To determine if you're getting a Cascoon, the game takes that massive number and performs a calculation. It basically looks at the last few digits. If the result of the calculation ends in a number greater than or equal to five, you get a Cascoon. If it's less than five, you’re stuck with Silcoon.
There is literally no way to change this.
You can’t use a specific stone. You can’t level it up at night versus during the day. You can’t feed it certain Berries or win Master Rank Contests with it. Once that Wurmple hits level 7, its fate is sealed. This has been the case since Pokémon Ruby and Sapphire launched on the Game Boy Advance back in 2002, and Game Freak hasn't changed the formula since.
Why You Can't Influence the Evolution
Some old-school rumors suggested that the "Nature" of the Pokémon—like Jolly, Adamant, or Modest—determined the evolution. That is 100% false. You can have a Modest Wurmple turn into a Cascoon, and you can have a Modest Wurmple turn into a Silcoon. The Nature is derived from the Personality Value, but it's a different part of the math.
Think of it like a credit card number. The first few digits might tell you it's a Visa, but the last few digits are what determine if the transaction goes through. In this case, the "transaction" is your Cascoon.
Where to Catch Cascoon Directly
If you're tired of the Wurmple roulette, the easiest way to answer the question of how to get Cascoon is to simply bypass the evolution stage entirely. Depending on which game you are playing, Cascoon pops up in the wild more often than you'd think.
In the Sinnoh region (Diamond, Pearl, Platinum and the Brilliant Diamond/Shining Pearl remakes), Cascoon is a staple of Eterna Forest. However, there's a catch. It's often version-exclusive. In the original Pokémon Pearl and the remake Shining Pearl, Cascoon is a common encounter. If you're playing Brilliant Diamond, you're almost exclusively going to find Silcoon.
- Eterna Forest: Walk through the tall grass. It’s a 10% to 20% encounter rate in the right versions.
- Honey Trees: If you’re feeling patient (or masochistic), slathering honey on golden trees in Sinnoh can net you a Cascoon.
- The Grand Underground: In the Gen 4 remakes, Cascoon appears in various "Hideaways" like the Grassland Cave or the Sunlit Cavern, but only after you've progressed a bit in the story.
In Pokémon Legends: Arceus, the rules change slightly. You can find Cascoon hanging out in the Obsidian Fieldlands, specifically around the Floaro Gardens and The Heartwood. The cool thing about Arceus is that you can see them in the overworld. If you see a purple cocoon, throw a ball. No math required.
The Legends: Arceus Exception
Speaking of Legends: Arceus, that game actually introduced a way to see the evolution before it happens, sort of. While the internal math is still there, the game’s UI makes it a bit more transparent once the Pokémon is ready to evolve. But even then, if you caught a Wurmple and it’s destined to be a Silcoon, nothing you do in the Hisui region will turn it into a Cascoon.
Interestingly, there’s a famous side quest in Legends: Arceus called "Wurmple’s Evolved!" where a guard named Beauregard wants to see his Wurmple evolve. Spoilers: it turns into a Cascoon, but he thinks it's a Silcoon. It's a funny nod to how confusing these two look to the average person.
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Step-by-Step for the Modern Player
If you are playing Pokémon GO, throw everything I just said about Personality Values out the window. Pokémon GO uses a completely different, though equally hidden, random number generator.
- Collect 12 Wurmple Candy. It’s a cheap evolution, which is a blessing.
- Check the "Evolve" button. It will show a silhouette with a question mark.
- Press the button and pray. In GO, there is no trick. There is no naming trick like with Eevee (where naming it "Linnea" gets you a Leafeon). It is a straight 50% toss-up. If you get three Silcoons in a row, you aren't doing anything wrong. You're just unlucky. The best strategy here is "volume." Catch every Wurmple you see. Eventually, the law of averages will kick in and you'll get your Cascoon.
Breeding for Success
Some people think breeding a Dustox will give you a "Cascoon-leaning" Wurmple. Sadly, that’s not how Pokémon genetics work in this universe. A Wurmple hatched from an egg is just as subject to the Personality Value calculation as one caught in the wild.
However, breeding is often faster than hunting in games where Wurmple is rare. If you have a Ditto and a Dustox (or a Beautifly), you can churn out eggs quickly. Since it only takes level 7 to evolve, you can test a batch of five Wurmples in about ten minutes of gameplay.
The Dustox Payoff
Why go through all this? Why obsess over how to get Cascoon?
Dustox is actually a bit of a niche powerhouse in certain early-game scenarios. It gets Confusion at level 10, which is a life-saver against the various Poison and Fighting types you run into early in most regions. Plus, its Hidden Ability, Compound Eyes (in some games) or Shield Dust, makes it surprisingly resilient against secondary effects like flinching or paralysis.
In the competitive scene? No, Cascoon and Dustox aren't winning World Championships. But for a Nuzlocke run, Cascoon is often preferred over Silcoon because Dustox is tankier than Beautifly. It can take a hit, throw out a Toxic, and stall.
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Practical Checklist for Your Hunt
If you're staring at a Wurmple right now, here is the reality check:
- Check your game version. If you're on Brilliant Diamond, stop hunting in Eterna Forest. You won't find it wild. Trade with a Shining Pearl player or use the Grand Underground.
- Don't waste items. Don't think that using a Moon Stone or Dusk Stone will help. It's level-based only.
- Catch in bulk. If you're in a game like Emerald or Alpha Sapphire, catch five or six Wurmples at once.
- Level them together. Use an Exp. Share to get the whole group to level 7 simultaneously. This is the most efficient way to bypass the 50/50 RNG frustration.
Essentially, getting a Cascoon is a lesson in patience and accepting that you can't control everything in the Pokémon world. The internal code is the boss here. Just keep catching, keep evolving, and eventually, that purple shell will appear.
The most effective next step is to head to a low-level area—like Route 101 in Hoenn or Route 204 in Sinnoh—and snag at least four Wurmples. Statistically, there's a 93.75% chance that at least one of those four will evolve into the Cascoon you're looking for. Go grab some Quick Balls or Net Balls and start the grind. It won't take as long as you think once you stop trying to "game" a system that is fundamentally un-gamable.