I think I got hypoaspis miles mites accidentally introduced to my terrarium. ID question

Earlier this year I introduced springtails and woodlice to my terrarium and within a few months, the springtail population exploded. A few months later and nearly all of them are dead and I'm pretty sure hypoaspis miles mites are the culprits, but I'm not sure. Can anyone help me ID this thing crawling on the snail's head? And if anyone has any idea how they accidentally found themselves in my tank. And if there is a way to have a good springtail population without changing the substrate. Thank you.