Okay, this is how I spawned him in both the farm house and the caverns (I recommend doing the 4 player difficulty trick). First, run out and get as many varkids to notice you. Second, keep shooting around them until you see a good amount of adult pods. Third, run to a good spot ( in the farmhouse or go left in the caverns and get behind the door) while still shooting. When you’re constantly shooting, you keep them interested in killing you, which causes them to not despawn. Also, you do not have to shoot them at all, I do just to get them to move or to get health back. This Method works because every time I did this method, I spawned him first time. If you cannot get him to spawn, then go to the other area. Btw, I have gotten a super badass to half health and he still podded up.
Maybe you just had insane luck, as (unless I’m mistaken) the spawn rate for Vermi is horrifically low, and only very slightly increased with the 4-player difficulty activated. Could be wrong though.
I’ve had pretty high spawn rates for Vermi when using the 4-player trick. Tundra Express offers the train as a killing method, but I prefer to get the varkids to aggro on one of the Crystalisks in Caustic Caverns. Then they’re all in one place, and you can focus on Vermi.
Well, the chance for any Larval Varkid to eventually become Vermivourous is about 0.042% for one player or about 1.68% for four which is a significant increase.
These are TVHM numbers. It’s impossible to spawn in Normal and it’s supposedly higher on UVHM but we don’t know about that. Not even the wiki tries to guess them.
Somehow I managed to reach Vermi solo… twice. That was when we had no idea how it would spawn.
I really miss the Bug Hunt event…
Yeah, he only has a 12% chance to spawn at max @TheRandomGoth . It takes me about 20 minutes to spawn him. And this method is faster because crystalisks cannot attack as fast as you can @Ronnie_Rayburn . When I have them agro crystalisks, only one or two ultras spawns in 20 minutes, where I can get two ultras and multiple supers in 5-10. Also, you have to dodge badasses while you wait for a crystalisk to spawn, and you only get that shed that has three ways for them to hit you for protection.
Neither method is really faster in that sense. Crystalisks work well because they have AOE attacks allowing them to aggro more Varkids at once leaving you a lot of breathing room. Unlike you, they (almost) can’t be killed by Varkids meaning they only very rarely lose interest as Crystals are always doing something which aggro’s enemies. It’s really funny watching them beat down on the Crystalisks to absolutely no avail.
It is still random overall and really just what you prefer. I personally prefer Caustic Caverns because there a lot more Varkids, willing scapegoats and cover around. I find many Ultmate Badasses in a few minutes, Vermivorous is rarer but their metamorphosis is just RNG after.
True, but the crystalisks do take time to spawn and they can agro you pretty easily. There would be times where I would be sitting there and they would randomly shoot one of their crystal bombs at me and I’d get hurt pretty badly. Also, when I have varkids agro crystalisks, I’ve seen ultras leave and despawn after a bit, so I guess it is preference. Also, I do round up varkids and let a lot of them pod up before I have them follow me to cover and shoot my fire infinity.
Good points. Enemy behavior isn’t always perfectly predictable after all. The despawning there can be terrible indeed 
I once had Vermy vanish into thin air right in front of me. That was just horrible.
Yeah. I think that it’s easier to spawn him at the farmhouse because the ultra has more room to pod up; where I farm him in the cavers, the area is taken up by supers and badasses.