I'm curious as to how you're going to prevent them from escaping when you move them out of the test tube. When I collected some workers of T. sessile in a jar with a screw-on lid, they just ran through the tiny space between the glass and the lid and crawled around my room (I was most unhappy!) until I put a piece of duct tape on the rim. Unfortunately, that made it air-tight! I've had the same problem with Monomorium minimum (one of my favorite species, too!) so I'd love to know how you solve that problem.