The University of Vermont
Physics Department
The University of Vermont
Physics Department
The Peacock Swallowtail
(Papilio Blumei)
The Peacock Swallowtail is native to Indonesia and utilizes structures to produce its colors. The scales of this butterfly are of the type II variety. In the previous section you compared this butterfly to the Blue Morpho and found that its color changed from green to blue when the viewing angle relative to the wings changed from straight down to almost edge on. Take another look at the specimen in the kit to verify this. The structure that produces the colors the Peacock Swallowtail presents is much different from that of the Blue Morpho, but uses some of the same physical phenomena.
Scanning electron microscope pictures (below) of the wing reveals bowl shaped structures on the surface of the wing. These bowls are made up of alternating layers of cuticle with pockets of air in between. These layers are just the
right thickness to form a structure that produces a multilayer thin film interference effect. Recall that the tree like structures on the Blue Morpho produced this effect for the blue wavelengths of light. But your observation of the color change with viewing angle indicates a structure that functions in a much different manner.
Take the LED flashlight that is fitted with a polarizer and set it on top of the plastic case over part of the green stripe on one side of the butterfly. Look at this illuminated area with another piece of polaroid from as high an angle as is possible. Rotate the polaroid until the brightness of the illuminated area is at a minimum. What color do you see? If the color of the wing is normally green what color is missing?
Vukusic 2001
Vukusic 2000
Vukusic 2001
Vukusic 2001
Vukusic 2001