As my Acromyrmex versicolor colonies are growing larger, I think they're going to need more than just a test tube to live in. I'm planning to make a very large vivarium formicarium to house my largest colony, but in the mean time, I'm going to have quite a few colonies large enough for a small formicarium like the one I have been working on for a while, but I'm not entirely sure that one will work right for this species of ants; I'll soon find out.
In the mean time, I decided to quickly throw something together that will probably provide them with what they need for now. It seems they like to keep a surplus of substrate just inside their test tube while keeping the entrance blocked off a lot of the time. I'm thinking they might be keeping this pile as far away from their fungus garden and humid end of the tube as possible so it doesn't start growing unwanted mold.
This should probably work well for them, and allow for some good visibility so I can easily observe them and get pictures.
The first tube is large enough for them to be able to bring in the larger pieces of substrate they usually store in their little pile. The smaller tube is there to segregate the large chamber from the first small one, and allow for a greater humidity difference between the two. The smaller the tube, the better it will help keep a humidity difference, so since they chew up the substrate into tiny pieces before putting it on the fungus, the smaller diameter shouldn't be a problem there. The hydration tank will just be a cylindrical container filled with a saturated sponge, screwed onto a stainless steel mesh wall at the large end of the container. This will hopefully make the larger container very humid--hopefully more humid than the test tube they're in now is. The smaller container should stay more dry, and hopefully that's where theyll keep their surplus of substrate. I'll be surprised if it really works out that way, but the most important thing is that they have more room, and more humidity, and they should definitely get that from this.
Here's the water tank. The liquid acrylic I used to hold the mesh down is absolutely uncontrollable without the perfect technique and equipment, which I don't have yet, so it looks a bit messy.