The geckos should be fine with preven a mite. Be careful with animals like chameleons that require spraying water. If you spray the cage with Provent a mite and then spray water on it for the lizard to drink the lizard could injest the poison.
:How safe is the provent a mite for animals such as knobtail geckos and chameleons? I took on the task of watching some bearded dragons and found mites on them. They are in a seperate room but they will probably find their way to the other animals. I do was my hands after working with them and work with them after everyone else is taken care of. :