In that case, it will be next to impossible without also drying out the plants and definitely the moss. Can you move the gecko to something new and start the setup over? Wild gathered moss almost always has slug, snail, and millipede eggs in it. Keeping it fully submerged under water for a few days could help prevent infestations. I also recommend rinsing it thoroughly.
"The ants are a people not strong, yet they prepare their meat in the summer." Prov. 30:25
Keep ordinary ants in extraordinary ways.