Queen of Spain

I have blipped this fritillary butterfly before, but this time the photo is much less summery! The temperature has increased a bit, but still this example decided to take time out from foraging away from the trees in blossom, giving me the chance to study its underwings..and, well, to photograph it. Last time I blipped about it I concentrated on the origin of the name of the butterfly, this time I decided to focus on the underwing/hindwing as I noticed it has got silvery patches which I'm afraid that I didn't manage to capture well enough on photo. In general the two sides of the butterfly's wings are totally different, the upper wing is used to attract the opposite sex and is therefore appealing and flashy, whereas the underwing is used for protection from predators and therefore often mimicks the vegetation in their usual habitat, like tree bark or leaves. That is why the silvery (well, metallic..or iridescent) patches left me grumbling. Don't they stand out? A research done on a similar butterfly, with silvery patches showed that the metallic appearance is caused by broadband reflections of the disordered three layer system of scales causing a uniform reflectance of light for all wavelengths in the visible range.  Maybe that explains how the predator's (mainly birds) vision is betrayed by the reflecting parts. I have also seen a theory that the silvery patches mimic dewdrops, don't know if anyone has tested that out. Apparently there are many research questions open in the field!