I know so little about insects, I have to admit I wasn't sure what this was – a butterfly, or a moth -- when it came in the house last night and tried to fly in between my glasses and my eye (that was something of a shock!). Finally it settled on the lamp next to me. It had been opening and closing its wings, which were quite colorful on the upper surfaces, but naturally it stopped when I got my camera. This morning it was gone from its perch, and I couldn’t find it anywhere, until it showed up on a curtain (but refused to pose), and then on the screen door, and I gratefully let it out.

POSTSCRIPT: Thanks to Tom, I can now say it was indeed a butterfly, a Painted Lady (Vanessa cardui). I wouldn't have thought there would be butterflies in such a harsh climate as we have in Riyadh, but obviously there are!