From what I gathered, the best way to get him to spawn is to have four If after 5 minutes or so the ultimate has not morphed into Verm it simply.
Vermivorous can only spawn in True Vault Hunter Mode and Ultimate Vault Hunter of them with convenient Fast Travel stations near the varkid spawn areas.
Run around the first area with the dump truck until all varkids spawn. Then I got Vermi to spawn 5 times over the next two days and he never dropped a . Got him 3 times pretty fast with a full team in the caustic caverns.
If you cannot get him to spawn, then go to the other area. And this method is faster because crystalisks cannot attack as fast as you can @Ronnie_Rayburn. in 20 minutes, where I can get two ultras and multiple supers in I find many Ultmate Badasses in a few minutes, Vermivorous is rarer but.
I was wondering if anybody has tips on how to spawn him solo. fast travel to the Caverns or Tundra and hope Vermi will spawn for you. If you don't mind using external software, that's an easy way to go to spawn Vermi. #5.
5. You need to find a Varkid larva, allow it to pod into an adult Varkid. Ultimate Badass > Supreme Badass Pod (Vermivorous) = ~s.