It's a minefield (or is it?)

Left, wild sorrel leaves that have been attacked by leaf miners, insects that lay their eggs under the surface of leaves where the larvae hatch out and consume the plant material from within. You can see one of the grubs at the bottom of the left hand mined area.

Right, lungwort leaves  with their characteristic white blotches. Variegated foliage is caused by a genetic mutation which could be expected to put the leaves at a disadvantage since the pale patches lack the ability to make chlorophyll which supplies the plant with energy. However in some species pale spots or blotches have become established which suggests they confer some survival advantage. One theory is that  the patterning makes it look as if leaf miners have already staked a claim and this deters new insects from laying eggs there.
An alternative theory is that plant leaves with white spots look as if they have been spattered with bird droppings and therefore grazing animals avoid them.

 (Defensive mimicry has been studied in a tropical plant which possesses both plain and variegated leaves, see here. I suppose it's a bit like installing a fake burglar alarm in the  hope that the mere sight of it will put off would-be intruders.)