That is just soo fascinating about them and their color changes..When I took Bumble out of the box he had blue bars that you could just see and as he got older they got more pronounced. Most of the time he's as David says, "old guacamole" color but at night when he goes to bed his bars turn yellow and his whole body is like a lime green color. When he gets upset the yellow stripes turn darker yellow and he gets black polka dots all over. As he got older more of the rust color came out around his mouth and on his knees and elbows. The fun part is when he gets upset or curious he pushes out the flaps at the base of his casque, like little tiny Dumbo ears! His color also brightens up when he's doing something that makes him happy, like being alone in his free range looking out the window.
I'll try to get a picture of him in his "pjs".