ON THE WINGS OF A BUTTERFLY.
This tiger swallowtail's wings are big and easy to see. But notice all the white markings along the wings' edges and the "tails" on this tiger. Scientists think these may work as targets for birds and other enemies. The marks and tails may fool birds into aiming for the wings' edges instead of the butterfly's body.
Butterflies have a good chance of surviving such edge attacks. Check out the butterflies in your area. Do you notice little cuts on their wings? Many of them come from attacks by birds.
To flutter by more butterfly-wing wonders, turn the page.
Hold a butterfly wing in your fingers (gently, please), and a kind of powder rubs off. That powder is actually thousands of tiny scales.
Scales cover the wings like overlapping shingles on a roof (see photos at right). Like shingles, the scales shed raindrops and help keep the wings dry.
The scales are really a kind of flattened hair. Some butterflies have regular hairs too (you can see some in the big photo at right). The hairs may help the butterflies stay warm.
See how each scale is one color? All together, the scales make a pattern on the butterfly's wings. Believe it or not, butterfly wings are colorless underneath the scales.
But where do the scales get their color? Some colors come from chemicals called pigments. Yellow, white, brown, black, and red scales are usually pigment-colored.
Other colors may appear when light hits the scales in a certain way (see box, above right). And some scales have both kinds of colors.
Some wing scales have tiny ridges on them. When light hits these ridges, it scatters in different directions. Then, as the scattered light enters our eyes, we see shimmery, shiny colors, like the ones on the sunset moth wing scales at right. These are called iridescent (ear-ih-DES-sent) colors.
THIS WAY, THAT WAY
The crow butterfly in the two photos above also has iridescent colors. The strange thing about this kind of color is, sometimes you see it and sometimes you don't. It all depends on how you look at it--or which way the light is shining. See how the blue area on this butterfly gets bigger and brighter?
As the butterfly flies through areas of light and shade in the forest, it seems to change color many times. Imagine how confusing those color changes would be to a bird that was trying to catch the butterfly.
Butterflies have four wings. The front two are called forewings and the back two are called hindwings. (See drawing below left.) When the insects are resting, they usually cover part of their hindwings with their forewings. With some kinds of butterflies, this coverup hides a big surprise.
Take the blue pansy butterfly below. If it's startled, the pansy moves its forewings forward and--shazam! Two bright eye spots stare out. Birds and other enemies may be spooked by the eye spots and back off.
TOP AND BOTTOM
When a comma butterfly spreads its wings, the insect is easy to see (above). But if it folds its wings up, the undersides tell a whole other story. The butterfly looks just like a dried-up leaf! (right)
So why does the comma spread its wings out, as it's doing in the top photo? It needs solar power. Butterflies have to warm up their wing muscles before they can fly. So they turn their wings toward the sunlight. The wings collect warmth for the muscles. Then, when the muscles are at least 78[degree sign] F (26[degree sign] C), the butterflies' wings can work.
See? Butterfly wings aren't just pretty--they're pretty tricky!
Tiger swallowtail scales below are 40 times actual size.