When you have a large healthy colony even the biggest outworlds, even adding two outworlds can't quite eliminate the issue of loitering ants. Basically, you'll have a number of ants that just hang out in the outworld. Not foraging, not exploring. Mostly just resting until the next hunk of dubia or fruit chunk shows up. And why not? From the ants perspective the outworld is just an overly bright, slightly less humid, mildly drafty nest. There are hardly ever any scary predators or attacking neighbor colonies. Why not just sit on the rock?
But, without the distinction between "outside" and "inside" ants miss out (and we miss out on watching) natural behaviors like signaling. No ant ever needs to run to get everyone from the nest when good food shows up. They are already there.
Loitering ants are also a problem for feeding and cleaning. Have you ever *dreaded* opening a particular outworld because they are on the walls, the lid everywhere?
Though, several of my colonies had a mild case of this problem the nicos are by far the worst. They have a massive nest. It's half full. They have two entrances to said nest. At last I relented and put a small wooden nest in their outworld hoping most of them would at least go inside ... But no, while a few took advantage literally 100s of ant were content to just loiter. And every time I had to change the water or food or clean I'd have an escape crisis on my hands. Yes I have fluon. Yes the outworld is large. They are just a big colony.
I started thinking about air circulation. The out world has two big mesh holes in the lid, which is pretty good-- but what if I tried a fan?
I bought a fan designed for reptiles and orchid on amazon.
Placed it on the lid on a medium setting. The ants didn't seem bothered, but I decided to wait.
A few hours later? Just about everyone was inside of the nest. They were even removing trash to make more space!
There are still a lot of ants in the outworld but they are mostly doing things, like drinking nectar and collecting food. I think it went from something like 300-400 ants loitering... to about 70-100.
The breeze from this fan is very mild but it's enough to keep the humidity and temp a little lower. The ants have and "outside" again! and I no longer dread cleaning and feeding them since I don't feel like I'm opening part of their nest when I do.