This year when my plants were in peak condition, the leaves started being stuck together with eggs inside. They hatched and burrowed through the leaves eating all the green and leaving the cellulose behind. They are small 5mm pale green caterpillars. The leaves then fall off and the flower heads withered. I used Ultimate Bug killer hoping the systemic action would work. It didn't. I cut back all the branches to the first leaf and re-sprayed. Problem is still there and the new leaves are dropping off after being attacked.
Skimmias Being Attacked by Bugs
Certified GKH Gardening Expert
This sounds like an infestation of leafminer caterpillars.
I am not sure what leafminer species would attack Skimmia, but this shrub is in the same family as citrus trees, so perhaps the citrus leafminer would:
You could also check with a local extension agent to find out what leafminer caterpillars are common in your area.
It can be difficult to control these with insecticides. The best control method is probably to search the plant for caterpillars and affected leaves frequently, and kill them or remove the affected leaves from the area.