Yellowish lines and curves on leaves

[Fuerte Rav]

Originally Posted by Ray

Having never seen them first-hand (knock on wood), I cannot be certain, but I recently read an article posted by a Dutch commercial grower about thrip damage becoming an increasing problem in their phalaenopsis/anthurium nursery, and the damage they showed looked similar.

EDIT: Found the link so you can decide for yourself.

Certainly looks like it and goes along with me not being able to find what I thought were the likely culprits such as scale or cochineal.
Thanks Ray, really useful!