What are the gold beads on a monarch butterfly chrysalis?

The gold spots on the Monarch chrysalis are a mystery that has inspired much curiOSity. The gold color is produced not by a pigment, but by structural iridescence. In other Words, the metallic luster you see results from the refraction of light from the multiple laminae (layers) of the cuticle of the pupa. The multiple colors seen when oil is spilled on water are produced in the same way. In an attempt to determine the function of these gold spots, Fred Urquhart conducted a series of controlled experiments in the early 1970s. He found that the destruction of these spots caused the wing scales to fade, or reduced the number of scales on the head or abdomen, depending on which spots were destroyed. From this he concluded that the gold spots are associated with scale formation and pigmentation; however, we still do not understand specifically how the gold spots influence these aspects of development. It is possible that the gold spots represent major sites of organization for wing tissue and/or epidermal cells.