My catasetum has recently developed these chlorotic spots. In a few places, there appear to be larger, irregularly shaped black spots, the largest of which is slightly translucent at the center. I have a second catasetum that has also started to display one or two of the small spots. I have thought thrips, spider mites, and cercospora, but I am fairly ignorant in this area and at a loss for what it is and what to do.
Something may be munching... look at the underside of the leaf and see if perhaps scale. Or it could be just on top. Would not be a bad idea to spray with Bayer's Advanced (or whatever they call it now) - spray both sides of the leaves. It does contain a miticide as well as insecticide (and Catasetinae are spider-mite magnets though that doesn't look like spider-mite damage)
It does look like you may be right Roberta. I just took a closer look at the rest of my plants. My Phal and my Peristeria elata look like something has been munching on them as well.