Hi Susanne,
Your little Rhv. is beautiful! And when I saw the photo with the white flower I was reminded of the first time I got a thrips infestation. It was like there was a sudden discoloration on my V. Sansai Blue...the petals were still holding up, only the color was gone like in your photo. When I got out my magnifying glass, I noticed the little buggers, and they literally removed an entire layer from the petals, thus stripping away the color. They were really hard to see, and very fast movers.
After a couple of applications of Orthene (about 7 to 10 days apart), I had no more problems with the thrips. It was an odd manifestation of thrips; as they usually just make the edges of the petals turn brown and thin, but I had a friend who has been growing chids a lot longer than me tell me that he has seen this before.
In any case, it may or may not be thrips...it might just be one of those odd things we see from time to time. I just thought that I'd put my
worth in.