Butterfly Wings

Photos by Lenora Larson.

The eye spots on the Buckeye Butterfly’s wings create the appearance of a larger animal’s eyes, complete with a white pigmented spot in the pupil. And even two spots to imitate nostrils! All combine to intimidate hungry predators. Macro-image of Monarch wing showing the scales.

Nature lovers embrace the “things with wings”, such as birds, dragonflies and the most beautiful of wings, butterflies. Lepidopterists believe that these brilliant daytime flyers evolved from the drab nocturnal moths about 60 million years ago although the reason is still controversial. Was it to escape bats, the most fearsome of nighttime insect predators? Or to enjoy the nectar of the newly evolving flowering plants? Either way, it was a case of going from the frying pan (bats) to the fire (birds), because birds are the primary daytime insect predators. Birds hunt by sight, so as part of this evolution, butterflies developed many colorful strategies during both the larval and adult stages to avoid being a menu item.

Form Follows Function

Butterflies have four wings, arranged in pairs, driven by the powerful flight muscles of their thorax. What functions do the wings serve? Obviously, locomotion. Butterflies have six legs for walking, but wings are the primary mode of transportation. However, the wings serve many other functions:

Balance: Butterflies land on flat-faced flowers to sip nectar and use their wings to balance during Midwestern wind gusts.

Body heat: The black pigment (melanin) acts as a solar panel to collect energy from the sun, which is why you see butterflies basking in the sun. Man-made solar panels have about 15% efficiency rating while a Black Swallowtail’s wings have up to an 88% efficiency in converting sunlight to heat.

Hearing: Did you know that butterflies have excellent hearing?

They will immediately fly at the crunch of a footstep or the snap of a shutter. Their “ears”, two tympanic membranes, are located on the forewing close to the body.

Protection: Potential diners are fooled through mimicry such as mimicking a face with huge eyes, or mimicking the color pattern of a poisonous butterfly, such as Viceroys and Painted Ladies, which both look like the poisonous Monarch. The reverse strategy is camouflage, brown or green to appear like a stick or leaf. There is considerable individual variation in butter-

fly wing patterns so that predators do not learn that butterfly’s pattern means a meal. Beginning butterfliers are frustrated when they find a butterfly that doesn’t match the field guides. You have not found a new species, you are experiencing “disruptive selection”.

Surprisingly, most butterflies do NOT use their colors and patterns for sexual recognition because to their eyes, these are not bright colors, rather a uniform ultraviolet glow. Butterflies see color very differently from birds and mammals because their eyes detect ultraviolet and infrared light. Sexual hook ups are facilitated by flight patterns and the aromas of powerful pheromones.

The Goatweed Leafwing provides an excellent example of wings as camouflage. The unseen top side is a brilliant orange. How Are the Colors Created?

Only butterflies and moths have scaly wings. These pigmented scales are modified hairs, loosely attached to expedite escape from spider webs. Loosing scales isn’t harmful and the wings of older butterflies are usually dull from scale loss during rainfall and mating. The scales are arranged like shingles on a roof, creating the patterns of color. The pigments are from plants eaten by the caterpillar and used in its own defense as well as stored in its body for the chrysalis and adult. Not all colors are pigments. Have you noticed that butterflies are not as colorful on a cloudy day? The structure of some scales creates a prism-like effect, refracting sunlight to create shimmering blues, greens and violets. Butterflies truly are flying rainbows!

LENORA LARSON Butterfly Maven

A Marais des Cygnes Master Gardener, Lenora is a member of the Idalia Butterfly Society and Kansas Native Plant Society. She gardens in the clay soil and cruel winds of Paola, KS. She may be contacted at lenora.longlips@gmail.com.