Butterfly Wing Scale Digital Image Gallery
Tiger Mimic Butterfly
The tiger mimic butterfly, alternatively known as Mechanitis polymnia, is a highly variable species that imitates the tiger-striped pattern of butterflies in three different genera. The variation of tiger mimics inspired a change in the belief systems of Victorian biologists. Instead of continuing to solely concentrate on fixed species, the scientists began considering issues such as natural selection, phenotypic shifts in natural populations, and the evolution of new species.
There are nine recognized subspecies of tiger mimic butterfly. However, no matter what its wing pattern, coloration, or sex, a tiger mimic butterfly can be identified by a characteristic round spot on the upper side of its forewings. The tiger mimic is the most widespread and abundant butterfly species in Costa Rica, where it can be observed flying on a regular basis in every city. Considered a weak flier, the boldly colored lepidopteran tends to frequent wind-sheltered areas. The tiger mimic, which is sometimes called the sweet oil butterfly, is unpalatable and extremely toxic to vertebrate predators. Thus, the species is beneficial to its fellow mimicry ring members because it reinforces avoidance behaviors in predators.
During the larval stage, tiger mimics feed in groups on the leaves of nightshades, especially the potato, eggplant and common nightshade, which are known for their toxic compounds. The larvae ingest and sequester the compounds that then serve as a defensive mechanism against vertebrate predators. However, they are not protected from parasitic wasps, flies, or spiders. Although not poisonous to predatory ants, tiger mimic caterpillars demonstrate a form of cryptochemistry or chemical camouflage that serves as protection from the insects. Since the caterpillars are able to sequester lipids from nightshade leaves into their cuticles, the larvae are chemically indistinguishable from their hosts and the ants do not recognize them as prey.
The tiger mimic butterfly and other representatives of the tiger-striped mimicry rings are popular with butterfly enthusiasts because of their clear illustration of intraspecific polymorphism and mimicry as a defensive strategy against predatory birds and lizards. Moreover, the slow wing beat of adult tiger mimics makes them easy to view and photograph and, therefore, the species is a favorite at butterfly gardens and conservatories. Unlike many Neotropical butterflies, which are at risk of extinction, the tiger mimic appears to not only be surviving, but also thriving.
Tiger Mimic Butterfly Images in Brightfield Illumination
Wing Scale Array - This brightfield image exhibits translucent layers of golden hued tiger mimic wing scales. Their ridged shape is beautifully displayed and the scales seem to hang down as if they were leaves on a tree.
Tiger Mimic Butterfly Images in Darkfield Illumination
Surface Texture of Wing Scales - The wing scales in this darkfield image display surface details that are not apparent in other techniques. The numerous rows of lightly textured scales seem to be standing at an upward angle.
Tiger Mimic Butterfly Images in Oblique Illumination
Flattened Wing Scales - In oblique illumination, the flattened wing scales of the tiger mimic appear to have a fairly rough texture, similar to shallow craters on the moon.
Tiger Mimic Butterfly Images in Reflected Light
Orange Wing Scales - This reflected light image displays the fiery orange shades that are most often associated with tiger mimics. However, various other hues may also be found on members of its nine subspecies.
Edge of Wing - This photomicrograph displays the delicate edge of a tiger mimic wing bordered with fur. The surrounding scales are warm shades of orange and brown.
Golden Wing Scales (Low Magnification) - Light reflects from the tiger mimic wing scales in this image in a way that gives them a metallic appearance. Shades of copper and gold seem to be majestically intertwined.
Golden Wing Scales (High Magnification) - The golden wing scales in this high magnification image appear like the shimmery skin of a snake.
Cynthia D. Kelly, Shannon H. Neaves, Laurence D. Zuckerman, and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.
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