A few months ago, a friend gave me a lithops as a gift and although I love lithops, I stopped keeping them because you can never have just one and it always gets out of hand. I have tried to be restrained and so far, I only have 4 pots of lithops.
The other day, a neighbour at work saw me packing some plants into my bag to take home and asked me if I knew how to keep lithops. I said yes and she replied that she gives up on hers, do I want them. I said sure! and went to collect them.
For those with sharp eyes: that's not a lithops, but a very long-suffering Pleiospilos nelii in the top left
This is what happens when people get carried away and spend a lot of money on plants they have no experience keeping: she didn't give them nearly enough water and they were seriously dehydrated. They had grown a full cycle with insufficient water and so were getting smaller and smaller. Although it's winter and it's best not to water them at this time, I decided to try and start rehydrating them immediately so I watered them thoroughly and removed the dried outer husks of the outer leaves.
Almost a week later, most are looking considerably better but the cleanup revealed another problem: mealiebugs
The white fluff is a sure sign of these pests and I found some live ones in among the leaf husks. It's unusual for Lithops to be attacked by mealiebugs and a consequence of them having been kept so dry: all plants are vulnerable to pests when they are water-stressed. I've sprayed with insecticide but I will have to use a systemic insecticide at the next water to be sure that they are gone, if I want these plants to thrive. I am keeping them indoors overnight so that the warmer night temperatures will stimulate them to start growing more actively and hopefully by this time next year, things will be very different.