Microscopy Image Gallery

Exploration of the Month

September 1997

There are many different things in nature that are beautifully patterned. Butterflies are one typical example. It is easy to see the patterns on a Monarch   wing, or a Red Admiral,   but there are many more beautiful patterns that can be seen with the help of a magnifier.

Monarch Butterfly wing Detail of Butterfly wing

The scales and hairs on a butterfly wing are responsible for the colors and patterns that we see. Some of the color is caused by pigments. Blue and green is a rare pigment in butterflies and moths although a common color of some butterfly wings. These colors are typically created by the microstructure of the hairs and scales which refract light to produce these colors and a metallic and iridescent effect, which seems to make the wings shimmer in the light.

Magnified tip of cabbage white egg Magnified detail of cabbage white egg

With the help of a magnifier it is possible to see that the wings of a butterfly are not the only beautifully patterned part. These two pictures show the egg of a Cabbage White   butterfly. The egg is only about 1mm in length, and looks white and fairly uninteresting when it is attached to the bottom of a cabbage or broccoli leaf. In the scanning electron microscope images shown here, the surface of the egg is covered with fine ridges. These look very similar to the sort of vaulting architecture that is used to hold up cathedral roofs, and probably help to keep the egg in shape. The images show details of the end of the egg, and the way that an extra ridge is incorporated into the egg wall; to makes the egg wider in the middle. At the tip of the extra ridge is a 5-sided area (all the others are 4-sided) which is a fairly unusual pattern in nature.

If you did not know how small this picture was do you think you could mistake it for something else? How about an ear of corn?

Close up of butterfly wing Higher magnification Butterfly wing scales

These six images show the wing scales in more detail. The scales overlap in rows similar to tiles on a roof and are actually modified hairs. In the three images above the wing is shown at increasing magnifications in the optical microscope. The lines of scales are barely visible in the first image, but are easily seen in the middle one. On the right is the highest magnification image where we can just begin to make out structures on the wing scales. Notice how each scale has a slightly different color.

The images below are a similar series taken in the scanning electron microscope. Notice how these images show the detail more clearly, but not the color of the scales. In the middle image, some scales have been dislodged from above this scale, showing the peg at the end of the scale which fits into a pore in the wing membrane. Because the scales are so loosely attached to the wing, it is very easy to dislodge them.

The highest magnification image on the right shows the open honeycomb-like architecture of the scale which makes them light and strong at the same time. On iridescent butterfly wing scales the size of these structures causes interference effects when light is reflected from them. The combination of the pigments and structural colors can create a very striking effect.

SEM image of butterfly scales SEM image of butterfly scale Higher magnification

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Last Update: 10/31/97