Flowers that Fly: Science of the Butterfly Wing
Butterflies are beautiful: Their eggs rival Faberge’s for sheer art. The migration of the Monarch butterfly holds navigational secrets still beyond our ken. But the wings are truly remarkable for their mimicry, polymorphism (variation) and aposematism (warning coloration). Like tiny shingles on a roof, microscopic overlapping scales cover the wings with brilliant, iridescent colors.
Structural Coloration: Black and brown colors are from melanin, but the blues, greens and reds are created by the microstructure of the scales and not by pigments. Originally observed by Robert Hooke and Isaac Newton, the principle of wave interference was described by Thomas Young a century later. Surfaces scored with fine parallel lines or thin layers on the same scale as the wavelength of light reflect multiple sets of waves. These can interfere with one another by adding or subtracting, to give rise to iridescence.
For more, see: http://en.wikipedia.org/wiki/Structural_coloration
A Quick Getaway: The scales of a butterfly wing readily detach, allowing for quick escape from a spider’s web or predator’s grasp. Thomas Eisner experimented by dropping various insects on a spider web. Of the butterflies and moths, he noted, “They all left impact marks on the webs where scales became detached to the viscid strands. Moth scars we came to call such telltale sites, and soon learned that they were common.” Most birds largely ignore butterflies. It turns out they are rather difficult to catch, without a large net, due to their erratic flying trajectories. Read Thomas Eisner’s essay on Butterfly Wings: http://goo.gl/5Sfon
• Beauty of the Butterfly Egg: http://goo.gl/0cnas
• Migration of the Monarch Butterfly: http://goo.gl/WuT6z
• If you like Opera: Maria Callas (Μαρία Κάλλας): Madama Butterfly – Puccini
• Blue-Butterfly Day by Robert Frost:
It is blue-butterfly day here in spring,
And with these sky-flakes down in flurry on flurry
There is more unmixed color on the wing
Than flowers will show for days unless they hurry.
But these are flowers that fly and all but sing:
And now from having ridden out desire
They lie closed over in the wind and cling
Where wheels have freshly sliced the April mire.