I got a Tetramorium caespitum queen last year and before hibernation she had about a dozen workers and some eggs etc. After hibernation I checked on the colony and everything seemed fine. They are living in a small glass tank with some loam, they have chosen a lump of loam which has gone very hard, almost like a stone, and dug into it. I have never seen these ants out foraging, I have only seen them when I lifted the stone to check they were still alive. I have never seen any evidence that they are taking food, but with the amount of ants in the colony - they must be. So I usually just check their food and water and leave them be.
Today I put half a grasshopper and half a pea in the tank, then waited 20 mins and went back to check - the queen was out foraging. I'm pretty sure it was the queen, the workers are very small and they don't have majors right?
Anyway, I see no reason for her to be out, there havent been any dead workers dumped outside of the nest, I checked the stone they live in and I don't see anything under there anymore, no eggs, brood or workers. just the queen out by herself wandering around. Did she eat her whole colony?
Mystery solved. unfortunately the ants had moved into a tiny crack in the hard loam on the bottom of the tank. I just moved a piece of wood and found a lot of dead ants. It was very dry there, so I think this is why they died. Damn!
WHat do I do with the poor queen now? Leave her to die slowly or put her out of her misery?
if it was me id put her back in a test tube.. offer her a small fly and keep her somwhere dark.. n hope she can start again.
I kept the basin very moist and just left her, she buried under the loam and I checked her periodically offering dry food, and this week, there is a tiny worker whizzing around. These ants are really tiny and fast. Anyway, seems like sometimes queens can recover when all their workers die :D