Wings of mimicry

17 Sep

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The early rising sun greeted us with a visitor in the damp grass one morning of a camping trip near New York’s Thousand Islands. As sunlight glistened on the blanketing dew, this large winged visitor rested on the grass waiting for moisture to evaporate off its wings and the sun to warm its body. It reminded me of another large moth, the luna moth (Actia luna), that I knew well during my life in the Maine woods.

The moth found on the wet grass that morning was a polyphemus moth (Antheraea polyphemus). Both moths are of the Giant Silkmoth family (Saturniidae). With a wingspan of up to six inches or more, the polyphemus moth is about the same size as a luna moth. These two species are the largest moths in continental America and may be found from Canada to northern Mexico.

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Male polyphemus moth (antenna are larger than female’s)

Polyphemus moths are generalists, which means they do not require a specific species of plant for the larvae to develop and survive. Females lay flat brown eggs on many species of decidous trees: elm, birch, willow, maple, beech, locust and a variety of Prunus species (cherry, plum, peach, etc). Like many Lepidoptera, polyphemus larvae develop through five stages and molts (instar). Unlike monarch butterflies, of which the instars are very similar in coloration, these moths have slightly different coloration with each instar. The fifth and final instar is an average of four inches long and a bright green color with silver spots on its sides. A caterpillar can devour about 86,000 times its weight from emergence to full development in two months.

From the photos of the adult moth below one can see hair-like body scales, small head and mouth parts, and the eye spots on the wings. Because of their small mouth parts, adults do not eat and only live for a week or less, during which their entire purpose is to avoid depredation and reproduce.

Mimicry

Mimicry throughout the animal kingdom is an example of natural selection in evolution. Ranging from mammals to tiny insects, mimicry may increase survival of individuals in their environment. Or it may reduce survival in another environment.

Lepidoptera are fascinating examples of how mimicry enables survival. One tactic is to mimic another insect that may be undesirable prey. Another tactic is the patterns and structures on butterfly and moth wings that mimic a component of their environment to hide from depredation. These tactics may be adaptive defense mechanisms (or artifacts of other patterns of coloration) in response to threats. Our polyphemus moth will serve as an example of mimicry as a defense mechanism.

Distraction Pattern

Like many saturniids the polyphemus moth has large ‘eye spots’ on its hind wings. These wing eye spots are translucent ‘windows’ which may be surrounded by bright colors. The pair of eye spots on the polyphemus hind wing are bordered by bright colors and, with the entire wing pattern, may resemble eyes of a predator. These are distraction patterns, which is a form of mimicry. They may resemble eyes of a different animal and confuse or deceive potential predators.

Wing eye spots can be a form of self-mimicry and a distraction pattern: to draw a predator’s attention away from the most vulnerable body parts or to appear as an inedible or dangerous animal. When threatened, adult polyphemus moths flash their  wings exposing the large hind wing eye spots to distract, startle, or scare off potential predators.

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The centers of the eye spots lack scales, so they are transparent.

Another example of distraction pattern in mimicry is camouflage which helps avoid detection by predators. Eye spots and wing color patterns on adult polyphemus can serve as blending camouflage (color matching) and pattern camouflage (pattern matching) in their environment.

Unrelated to mimicry, these eye spots may also play a role in mate attraction, but this has not been conclusively confirmed.

dscn1811-sMimicry is also exhibited by the polyphemus caterpillars. They can be protected from predators by their cryptic green coloration (another example of what kind of distraction pattern?). When threatened the caterpillars often raise the front part of the body up in a threatening pose. If attacked, the caterpillars make a clicking noise with the mandibles.  This clicking is associated with a distasteful fluid exuded by the caterpillars which can cause regurgitation by the attacker. Some animals (squirrels, birds, other insects) are deterred by the ingestion and regurgitation and the clicking may serve as a warning.

Mimicry and names

Since one of my interests is the etymology of animal binomial names (simply put, the naming of things), mimicry also plays a part in this moth’s name.

The four silkmoth species in the New World (the Americas) were assigned to either Telea or Metosamia genus. The polyphemus silkmoth in the Americas was first described and named by Dutch naturalist Pieter Cramer in 1776 as Telea polyphemus. Jacob Hübner, a German entomologist (1761-1826), assigned the Old World (endemic to Asia and Europe) silkmoths to the genus Antheraea in 1819.  In 1952, American entomologist Charles Duncan Michener (1918-2015) systematically categorized the Telea and Metosamia in with Antheraea classification. All the silkmoths are now in one genus classification.

The Modern Latin genus name Antheraea likely derives from the Greek anthēros, meaning brightly colored, brilliant, or flowery.  The Lepidoptera Antheraea type species (the species on which the description of a genus is based on, and with which the genus name remains associated during any taxonomic revision) is the beautiful and vibrantly-colored tasar silkworm (Antheraea mylitta, formerly Phalaena mylitta), named and characterized in 1773 by English entomologist Dru Drury. Although not a silkworm like the tasar species, the polyphemus is colorful and has similar eye spots.

Cramer’s choice of the species name was based on Polyphemus, the giant cyclops from Greek mythology who had a single large, round eye in the middle of his forehead. Cramer may have been reminded of the name because of the large eye spots in the middle of the hind wings.

And the commonly used name ‘sphinx’ moth?  It could have arisen because of the behavior of threatened larvae. When they raise their heads and thoraxes up, the pose superficially resembles Egyptian sphinxes. Someone had imagination.

Of course, the family name Saturniidae  also peaked my curiosity.  The consensus is that it was based on the eye spots of some members of the family that contain concentric rings reminiscent of the planet Saturn. I’ll take that, too.

 

Heading to the moon

16 Sep

This morning
Songs of geese
heading to the moon.

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The Grandfather Rock and its children

15 Sep

Summer has been busy with family and work on the refuge. A four-day weekend was welcomed, especially by the lake. I took advantage of some down time and brought my sketch book with me, finishing a sketch started a year ago while hiking around Fish Lake on Steens Mountain in southeast Oregon.

A windy and chilly day at nearly 8,00 feet, but every day on Steens Mountain is glorious. The wind whipped the deeper water surface only the middle of the lake. The group of poplars on the opposite shore were home to a nesting pair of ospreys. Watching the immature siblings practice their hunting, kiting, and diving skills was an immense thrill. One of the adults interrupted them to demonstrate how it’s done. After the adult rose from the water with a fish, it shook the water off its feathers, flew to an aspen tree branch with its meal, and seemed to taunt the offspring by standing on its fish while glaring at them.

I sat on a bare spot of ground next to the water and sketched two pages. A section of the lake and two plants near me. I watched and listened. I finished the lake sketch just now. It’s as if I was there, right now.

I remember, and still feel the peace there.

Steens Mountain is a Grandfather Rock. It has many, many stories to tell if one is willing to listen. And many Children live on its skin: elk, hawks, mule deer, coyotes, badgers, butterflies, lichen, mosses, sagebrush, pines, aspens, and so many more. When visiting, listening, and being respectful, you will learn many stories, like sitting at the feet or in the lap of a Great Grandfather.

When I am there,
I am just a Child,
eager to learn the stories.

A planetary merry-go-round

19 Aug

It is already 95 degrees F and about 85% humidity. Rain fell just 400 feet from the window where I sit with a cold ice tea.

I just read an article taking readers back in time to the supercontinent Rodinia, then the big (and my favorite) supercontinent Pangea. Then the epoch of volcanoes, and rapidly forward to the apes walking upright on the savannahs.

And I get a feeling that I’m riding a rocking horse through time, whizzing through the birth and growth of this merry-go-round.

I’m like an alien kid, loving the ride, and hugging the realization that we humans are a speck on a golf ball whirling around a lightbulb in a giant arena of wonder.

And I feel fine.

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A Path with Heart

17 Jul

On mountains I lose myself and become one and nothing with everything, and I see things clearly.

To know happiness, one must know pain. To know joy, one must know sadness. To welcome the day, one must know the night. To rejoice in life, one must know death.

The yin and yang is present in all life, in all non-life. It is the Way of everything. Where there is a positive, there is a negative. We cannot always choose one or the other, sometimes it chooses us. To know both helps us to choose a path. But we should not choose to deny that which we don’t want to choose. Otherwise we may fall into that path unknowingly. It is how that path chooses us.

Denial is choosing blindness, and then blindly we may tumble onto the wrong path. We live on a dynamic journey that with each step we learn and navigate by following what we think is right. That journey may twist and turn with several obstacles in the way, some with demons. But to face the demons, and conquer them, yet still acknowledging that they exist, makes us stronger and informs our choices in the Path with Heart.

Enjoy your day and follow a path that has heart.

Steens Mountain, SE Oregon

Night Angels

12 Jun

I am surrounded by hundreds of fireflies.
They are the stars and angels.
I am in the heavens of the universe.

Nature in Photography

6 Feb

A week or so ago on FaceBook I was nominated by two friends to participate in the #challengeonnaturephotography meme. Although I rarely participate in these memes, the thought “Why not?” prompted me to give it a try. The protocol is to post a nature-themed photograph, include the hashtag, give kudos to the friend that nominated you, and then nominate another friend in the caption.

I played by the rules for three days. Then life got in the way (long days in the field), and I got lazy. I posted when I had time, dropped the official hashtag, the nominators, and ran out of FB friends to nominate. I keep my FB friends to a relatively small number (up to 50 now!), and friends who are into photography have already participated once or twice.

Now I submit a story with the photograph instead. Why? Because photography to me is a storytelling medium. Today’s photograph is a glimpse into the secret lives on the ‘little people’.

Nearly every day for three months last summer, I was privy to an entire world few of us see in depth and detail. I felt like a giant studying, learning, and enjoying a network of soil, water, plants, and insects……….at their level. Sometimes I was so giddy with childlike delight, I forgot who and what I was. And I was full of anger and intense sadness when part of this magical world was destroyed by humans. That, too, was a lesson I won’t forget.

Revealed below is a monarch butterfly larva and several cobalt blue beetles all ‘doing their thing’. They use milkweed as a common food source. Yet they tolerate each other. I have watched members of both species consume leaf material, side by side without conflict. Here, two beetles are copulating, undisturbed and unfettered. While the monarch voraciously chows down, preparing to form its chrysalis. This, however, is only one tiny window into the lives that live in the ecosystem in which I immersed myself.

Most nature photography depicts landscapes of empty agents and actors. Or portraits of animals, still and silent in pose like a person sitting for a photograph. To me this is an injustice to the inhabitants of the landscape as they live out their drama and narratives in those spaces. Few ‘nature’ photographs reveal the complex interrelationships within the landscapes and with their fellow animals. They fail to show the communities of life in places other than within our own human preconceptions and expectations. As if we strive to capture and show only a snapshot in time and space that suits what we want to see.

In addition to the beauty, the silence and solace depicted in landscape and wildlife portrait photography is a dynamic world of creatures living their lives just like we do. The drama, the beauty, the good and bad, birth and death, at every level; from micro to macro. There are stories out there that are not of our own.

And we can learn from them: About their lives, their interactions with each other and how we interact with them. We can even learn about ourselves.

Think about that the next time you are out in the natural world. Take time to observe before you press on that shutter release button. You never know what you might find.

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Fifth instar monarch larva and cobalt blue beetles on showy milkweed.

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