I'm fighting mealy-bugs again. Is there a way to get rid of them for good? It is an epic battle, really. The only good thing about mealy-bugs is that they kill slowly and you can rescue the plant in time if you notice them (which means you notice that the plant isn't doing so well). The bad thing is they just crawl back from other pots. Re-potting the whole collection and growing them in vacuum after that may help, I guess. Is there something you can add to the soil mix or something that can be dissolved in water to keep them away? Spraying is obviously pointless.
On this occasion I've made a video on how to transplant a lithops plant into pumice/bims. Some people seem to have troubles with it. It works best if the stones aren't dry as dust (but also not wet, of course). The pumice you see in the video is just like it comes from cono's paradise.