Yeah I did and they get wet originally but then they start drying back out. How should I go about ripping off pieces with the ants inside?
Yeah you probably won't be able to. I would fill up another test tube and make the cotton ball smaller on that one, and then if you have a way to connect the test tubes together via an adapter or something you could do that. If they're not tiny ants you should be able to just place the mouths of the test tubes together and hopefully they'll eventually move. Heating the dry side of the test tube you want them to move to may help, but I'm always leery of heating test tubes as it can go bad quickly, so just monitor it closely if you do.
Another option is if you have an escape proof container, you could set the test tubes next to each other inside and let them move themselves into the moist one. I've noticed some ants won't do this as they just will drink the water from the neighboring test tube and stay in the dry one, but it usually works for me.
Depending on the species you may need quite a bit of patience. I've had some take minutes to move, and some weeks.