These lithops seedlings were sown in October. I wasn't expecting them to divide this year, but they are. But I seem to bee loosing some, maybe 20% or so. They go white and die. Does anyone now why some should die now? Is it something I'm doing/not doing? The rest seem healthy

Oh they are so cute..but sad to see them die..am never good at lithops..but as for your question..what are the temps like in the location they are planted in?

Temperatures have been very up and down over the last 2 weeks or so, anything from 22 deg C to 0. We had a very sunny fortnight when it was warm but now we're having hail and sleet again (although obviously they are inside on the windowsill!! I wonder if the bright sun, that came very unexpectedly after months of rain and could might have cooked them?

Could be a combination of things..cold draft by the window or as you said the sudden heat..intensified as it goes through the window.

Yes I think they don't like direct sunlight Kate!
But I agree how cute!!! Very cool!

That would explain it then. Oh well, survival of the fittest and all that, and they need to be pretty fit to survive at my hand ;)