Something eating my Cyrtorchis?

Hello. Would like some help in trying to identify the cause of several little holes in the leaves of my Cyrtorchis chailluana.
It is a recent arrival from a nursery and has several isolated holes in a few of the leaves.
I don't know if this is caused by something eating them (the holes are quite round, rather than elongated like the damage caused by moving snails), or if they have been burnt through by splashed fertiliser. I have not had the plants long enough to have seen the evolution of the holes, but they are straight through the leaves, as I hope the photos show well. (The shine on the leaves in the second photo is from a recent misting, and the holes are otherwise dry, no signs of mushiness.)
I evicted some tiny spiders from the plant after bringing it back from the vendor, but I don't know if they would have caused spots like this.
I would be grateful for any diagnosis and advice.
Many thanks,
BR

 

Good idea, many thanks for the advice. I will give that a go. At least there are no new holes since I brought it home, but a tape trap might be a good way to make sure it stays that way. Thanks again.