The brightest beetle we’ve seen, and help identifying bugs

As long as I was on the topic of beetles, I thought I’d include this one which my husband photographed on Mt. Ashland in August during one of our wildflower walks.

Desmocerus aureipennis, male Elderberry Longhorn Beetle

The best resource I have found for identifying insects, if they are not among those illustrated in our insect field guides, is by using BugGuide.net. If you can narrow your search down, you may be able to identify it yourself by looking through the extensive pages of thumbnail photos for each group, genus, and species. That is how I figured out what this was,

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a spider named Cyclosa conica, for an earlier post—but I had to scan through dozens of pages of thumbnails to find this particular individual.

There’s another way: submit at least one good photo of the insect or arachnid in question to bugguide.net, with relevant details such as geographic location, time of year you saw it, and where (in your attic? under a log? on a rose bush?). Then a group of people who know lots more about bugs than you or I, will take a look, there will be perhaps some back and forth, and you’ll probably get a consensus. Before posting your photos you need to register an account with username and password, then after that you can log in and look at your photos and see what has been said about them.

BugGuide.net is hosted by Iowa State University Entomology, and a lot of the responders are extremely knowledgeable. Also, it is a collegial effort—they check each other’s work, in effect. But of course if the answer is really important to you: if this spider just bit you and your arm is swelling, or you have an orchard infestation of some bug, you want to talk to a real live person like a doctor or an ag extension agent. Try to get the bug into a little jar and take it with you.

This is a fun and educational site to browse through. There are pages of many-legged creatures awaiting identification (the better your photo, the better your chances, but send the photos you have), and of course a structure of pages organized by taxonomy, order/family/genus. Even better, on the left of each page is a visual key, a clickable guide composed of bugs by shape, to help you get close to the creature you are interested in.

The big red bug was not in our guides so I submitted it and got a precise ID. It is a Desmocerus aureipennis/auripennis, male. The females don’t have the bright red elytra, or wing covers. It’s one of a group called Elderberry Longhorn Beetles, and our photo showed it on that tree. I looked up other photos of this insect and yes, that’s what it is.

[Etymological note: desmocerus from the Greek desmos (banded or fettered) + keros (a horn) and aureipennis from the Latin aureus (golden) + penna (feather, wing).]

Biggest bug I was ever bitten by

One day this summer I was at the school where the food pantry is held, and a school landscape employee was spraying weeds. He called out in surprise, that there was a really big bug right on the nozzle of the herbicide applicator. I ran over to see and apparently was the only person willing to pick up this huge black beetle. I decided to take him home, since my husband is a beetle fancier, and rummaged around for some sort of container for him. Finally I found a kleenex box, emptied it, and with the help of a young girl gathered leaves and sticks to make a cozy temporary home. The little girl was scared of the beetle but her feelings toward him began to turn warm and nurturing when I invited her to help furnish his house. She hadn’t gotten up to touching him by the time we put him in and taped a piece of paper over the top, but given more time I feel sure she would have come around.

Here’s our prize, emerging from his house (all the furnishings got shaken to a corner by the car ride).

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He crawled on my arm and hand for a while and then I must have annoyed him because he bit me with his mandibles—made me jump! The bite made a 1/8 inch cut that did bleed, but alas left no scar for me to show off while admitting how I had completely deserved it. Below he’s on my husband’s arm.

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And for better scale,

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We were able to identify him as one of the longhorned woodboring beetles, the Spined Woodborer or Pine Sawyer Beetle (Ergates spiculatus). One clue to differentiating him from another similar species was the spininess of his thorax, visible in this photo. The spines are on the sides of his thorax, while the yellow arrows point to the palps which unfortunately are blurry in this picture.

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Here the palps are clearer.

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The palps are sensory organs for the beetle. Mandibles cut up food and maxilla help manipulate it. The parts of a beetle’s head are shown in this illustration.

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After irritating this beetle so much, we stopped before getting any good photos of his underside, though we could see intriguing edges of fibrous stuff. Here’s someone else’s great picture of what the description says are “velvety” underparts. The eyes and two pairs of palps are also shown.

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Etymological note: ergates is from the Greek, worker; spiculatus, from the Latin spiculum, a little sharp point (diminutive of spicum, a sharp point). The English word “spike” may derive from this Latin word, or may have a more indirect derivation; there is a Proto-Indo-European root *spei-, sharp point. [Proto-Indo-European is the common ancestor of all modern Indo-European languages. It dates from before writing, so it has been reconstructed from study of related words in various languages, and derivation of rules by which sounds change over time. The same method has been used to construct Proto-Germanic. In historical linguistic studies, the asterisk next to a “word” means that it is a reconstructed root.]

One site says this is the largest beetle in North America, up to 65 mm (2.6 inches) in length, but I could not confirm its status as champion big beetle. At any rate it is plenty large, and I wondered if it was one of those beetles, the larvae of which cause extensive die-off in our Pacific Northwest forests. A publication on wood-borers from Washington State University reassured me: “Keep in mind that almost all of our native species of long horned beetles feed in dying or stressed trees and do not attack healthy trees”. According to them, Ergates spiculatus feeds mostly on dead/dying/stressed Douglas firs or Ponderosa Pines.

That information has a different implication, however, at a time when climate change may be stressing northern forests with increased temperatures and long droughts, causing millions of trees to fall into that “stressed” category. British Columbia has reportedly lost about half of its pine trees to a borer no larger than a grain of rice, which spends most of its life boring beneath the bark, a process continued by its larvae which cut off the nutrient and water supply while feeding. To make matters worse, “The beetles also introduce a distinct blue stained fungus that holds back a tree’s natural defences against the attack, delivering a lethal larvae and fungus combination”.

Our trees look pretty good, though, so without hesitation we turned the big biting bug loose on one of them.

Ergates spiculatus Spined woodborer on tree.jpg

Western Tiger Swallowtail butterfly, and a very close look at butterfly wing-color

We’ve gotten a few terrific photos of butterflies this year—some posted here and here— but none of the swallowtails has cooperated by alighting within range. When I saw one that had died and fallen to the road I carefully carried it home for the chance to get a close look.

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There are at least three very similar species of swallowtail around here—the Anise, Western Tiger, and Oregon Swallowtails. Based on the red and blue markings I’m thinking this is the Western Tiger Swallowtail, Papilio rutulus.

Finer than “frog hair”—butterfly hair!

Enlarging the macro photos shows details such as hairs on the body and along the inner edges of the wings.

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These hairs, called tactile setae, are attached to nerve cells, which relay information about the hairs’ movement to the butterfly. … Adults have tactile setae on almost all of their body parts. In both adults and larvae [caterpillars], the setae play an important role in helping the butterfly sense the relative position of many body parts (e.g., where is the second segment of the thorax in relation to the third segment). This is especially important for flight, and there are several collections of specialized setae and nerves that help the adult sense wind, gravity, and the position of head, body, wings, legs, antennae, and other body parts. In monarchs, setae on the adult’s antennae sense both touch and smell. (from monarchwatch.com).

In the photo below, a ventral view of the lower wings where they meet at their lowest point, there is also a delicate fringe visible along the edges. This could have aerodynamic as well as sensory functions.

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From pointillism to nanostructures

Parts of the markings that appear as solid areas to our eye are revealed to be pointillist creations. I suspect we would need to know much more than we do about the vision of butterflies (and their predators?), in order to understand how these markings work for them.

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The odd squareness of the smallest dots of color is not some pixellation in the photo, but an accurate representation. It shows the shape of the overlapping scales which form the surface of butterfly wings. Here are some microphotographs of wing scales at various magnifications, from Wikipedia.

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And here are color microphotographs showing the same squared-off dots along with the underlying scale pattern.

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Picture source.


It’s been known for some time that the colors of butterfly wings are partly from pigments but mostly from the microstructure of the scales, scattering light to produce the colors. Blues, greens, reds and iridescence are usually structural, while blacks and browns come from pigments. (Wikipedia).

But now we know more, and the more we know the more intricate and amazing it is. Research (published this past June) has been able to identify the light-scattering shapes from the wings of several butterfly species, and they are described as “ ’mind-bendingly weird’ three-dimensional curving structures… [resembling] a network of three-bladed boomerangs”. The name for these crystalline forms is gyroids, and they were first described

in 1970 by NASA physicist Alan Schoen in his theoretical search for ultra-light, ultra-strong materials for use in space. Gyroids have what’s known as an ‘infinitely connected triply periodic minimal surface’: for a given set of boundaries, they have the smallest possible surface area. The principle can be illustrated in soap film on a wireframe (see image below). Unlike soap film, however, the planes of a gyroid’s surface never intersect. As mathematicians showed in the decades following Schoen’s discovery, gyroids also contain no straight lines, and can never be divided into symmetrical parts. (source, text and soap-bubble photo: wiredscience.com)

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Gyroid-like soap bubble. Photo from wiredscience.com

So gyroids were introduced to humans as an imagined created form, something that is a mind-boggler for non-mathematicians to envision.

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The image above is a mathematician’s representation of one of the simpler types of gyroid.

Materials scientists have learned how to make synthetic gyroids for photonic devices, such as solar cells and communication systems, that manipulate the flow of light.

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A self-assembled solar cell begins with one of two polymers forming a “gyroid” shape while the other fills in the space around it. The inner polymer is dissolved away to create a mold that is filled with a conductor of electrons. The outer polymer is then burned away, the conductor is coated with a photosensitive dye, and finally the surrounding space is filled with a conductor of positive “holes”. A solar reaction takes place at all the interfaces throughout the material, and the interlocking gyroid structure efficiently carries away the current. (Source for image and caption, Cornell Univ.)

And when Yale evolutionary ornithologist Richard Prum got curious about exactly how butterfly wing-scales twisted light, he found gyroids. His team had to use an advanced microscopy technique with nanoscale resolution, called synchrotron small angle X-ray scattering, in order to see them, but there they were. (See note at end for citation of article in PNAS.)

The butterfly’s gyroids are made of chitin, not exactly the flashy material I would associate with iridescent wings. It’s

the tough starchy material that forms the exterior of insects and crustaceans. Chitin is usually deposited on the outer membranes of cells. The Yale team wanted to know how a cell can sculpt itself into this extraordinary form, which resembles a network of three-bladed boomerangs. They found that, essentially, the outer membranes of the butterfly wing scale cells grow and fold into the interior of the cells. The membranes then form a double gyroid—or two, mirror-image networks shaped by the outer and inner cell membranes. Double gyroids are easier to self assemble but they are not as good at scattering light as a single gyroids. Chitin is then deposited in the outer gyroid to create a single solid crystal. The cell then dies, leaving behind the crystal nanostructures on the butterfly wing.

“Like engineers, butterflies grow their optically efficient single gyroids through a series of steps that make this complex shape easier to achieve. Photonic engineers are using gyroid shapes to try to create more efficient solar cells and, by mimicking nature, may be able to produce more efficient optical devices as well,” Prum said. (Source)

In an interview about the work, Richard Prum said “We’re still trying to wrap our brains around gyroids and what they are.” The shapes seem to have evolved separately in several lineages of butterflies.

”It’s a Swiss cheese,” he adds, “with spiraling channels of air traveling through it that intersect one another. But those channels actually travel in three different dimensions through the cheese, and what you end up with is this very complicated form left behind, and that form is a gyroid.”

And while the idea of butterflies with Swiss cheese wings is slightly strange, Prum says it’s a very useful one for scientist and engineers looking for the next leap forward in electronic technology.

For example, Prum says, take the fiber-optic cables that carry phone calls under the ocean. These cables carry signals in the form of colored light, but it’s very difficult to insulate them well enough to prevent light from leaking out. Current transoceanic cables have to have booster stations built along them to keep the signal strong. But a layer of gyroids around the fiber-optic cable “would act like a perfect insulation to that fiber,” Prum says. The same tiny structures that give the Emerald-patched Cattleheart its lovely green patches could also be used to keep green light from escaping a fiber-optic cable.

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The vivid green color of the scales of this Papilionid butterfly are produced by optically efficient single gyroid photonic crystals. Caption and photo from www.physorg.com

Right now, it’s expensive and impractical to manufacture gyroids small enough to do that job. But butterflies hold the secret to growing them naturally. “If you could grow one, at exactly the right scale, as butterflies do,” says Prum, “you could make these things a lot easier.” (NPR interview, Jul 3, 2010)

This is a fine example of how curiosity can lead us to unexpected discoveries. The original question is one that could be used by certain Congressional anti-intellectuals in their periodic efforts to discredit basic research: “Imagine, all this work to find out what makes the color on butterfly wings! How ridiculous!” The research and technological developments that are thought “useful” by these folks had their origins in someone’s basic research, sparked by human curiosity. From butterfly wing-color to, perhaps, more efficient fiber-optic cables or solar energy collectors. It’s called bioengineering: investigating the functions and structures of nature, to derive principles and patterns for technological innovations. But for me it’s satisfying in itself, the revelation of these marvelous structures, underlying the evanescent beauty of a butterfly.

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Western Tiger Swallowtail butterfly on Buddleia bloom. Photo by terwilliger911, flickr.

Note: The article describing gyroids as the structure causing some colors in butterfly wings is:
Structure, function, and self-assembly of single network gyroid (I4132) photonic crystals in butterfly wing scales.
Vinodkumar Saranathan et al. Proceedings of the National Academy of Sciences. Published online before print June 14, 2010, doi: 10.1073/pnas.0909616107. The abstract is available free, but the article requires purchase or subscription to PNAS. There is a supplementary article here that contains some interesting images and very technical text. There’s even a movie you can watch showing a slice-by-slice trip through a certain sort of gyroid, or as the text says, though “the pentacontinuous volume of a level set core-shell double gyroid structure”.

We brake for butterflies

Butterflies everywhere in the air! so many you have to drive about 5 miles an hour, letting the current of your progress gently push them out of the way. That’s how it was one morning last week, on the paved forest road where we often walk. By 3 pm it would be 100°. Though there were still wildflowers in bloom, these butterflies seemed not to be feeding, but mostly just flying and chasing one another. Breeding season? One did land for a moment on Dan’s finger and another swooped at it aggressively, over and over.

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California Sister butterflies (Adelpha bredowii), ventral view.

As before, in a different location on this road, we saw scores of the California Sister butterfly (Adelpha bredowii) but this time none of the Lorquin’s admiral (Limenitis lorquinii) seen then. Swallowtails were present too, like sunlight in flight, but in small numbers. Unlike the others, the swallowtails never lighted for long either on vegetation or on the road, where the California Sisters clustered to get minerals from visible animal scat or from remains too small for us to see.

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California Sister butterfly, dorsal view, on the road.

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This ant was pulling along the body of a California Sister butterfly. It would move the butterfly an inch or two, then stop and scurry around looking (I thought) for a more effective place to grab on.

Swallowtail butterflies

The swallowtails never let us get close enough for a really good look or photo, and we may even have seen more than one species. Dan, whose eyes are better, says that most were a pale yellow. the others brighter. Of the three found in our area, one is a species called the Pale Swallowtail (Papilio eurymedon) that uses Ceanothus spp. for its larval host plant, and Blueblossom ceanothus (Ceanothus thyrsiflorus) is a common flowering shrub here. Very pretty too, growing to 6 feet or more in height and flowering in varying shades of blue and lilac. Most are past their peak of bloom now, beginning to fade or entirely withered; these photos are from June.

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The British biologist J. S. B. Haldane was engaged in discussion with an eminent theologian. ‘What inference,’ asked the latter, ‘might one draw about the nature of God from a study of his works?’ Haldane replied: ‘An inordinate fondness for beetles.’ Indeed, of the 1.5 million described species on the planet, 350,000 are beetles, more species than in the entire plant kingdom. So I didn’t even try to identify the mating beetles in the photo above, but Dan picked up Insects of the Pacific Northwest (by Haggard and Haggard) and found them easily: Anastrangalia laetifica, the Dimorphic Long-horned Beetle! The female’s red wingcovers are visible on the right side, beneath the male’s all-black back.

This is the Pale Swallowtail, below. [Photo by Franco Folini, from flickr]

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Different life stages of the Pale Swallowtail caterpillar are shown here, and for the Anise Swallowtail here. Caterpillars can have quite different appearances, as they pass through successive moults (stages called instars), and so the one illustrated in your field guide for a given species may not look at all like the one you find.

The other Swallowtails likely to be seen here in Southwestern Oregon are the Anise Swallowtail (Papilio zelicaon) and the Western Tiger Swallowtail (P. rutulus). Oregon’s state insect is the Oregon Swallowtail (P. oregonius, sometimes called P. bairdii) but it’s found in the dry sagebrush canyons of Eastern Oregon and Washington along with its caterpillar host plant Tarragon or Dragon’s-wort (Artemisia dracunculus). Our culinary tarragons are varieties of this same species.

A web furnished for concealment, Cyclosa conica

Yesterday’s forest walk, along an alarmingly narrow dirt road next to a hundred-foot drop, introduced us to Cyclosa conica

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a spider with an unusual tactic for concealment. On its web it makes a vertical strip of reinforced filaments, called a stabilimentum, to which it adds the husks of its prey. Females often place their egg sacs in the stabilimentum too. Then the spider hides itself at the center of this little visual interference area it has made, while it waits for insects to fly into the web.

The vertical strip of insect remains is clear in the photo above, and here’s a closer look at the arachnid itself.

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The stabilimentum is used in various forms by other orb-weaver spiders (family Araneidae, the builders of spiral wheel-shaped webs).

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Above, the “Writing or Signature Spider”, Argiope sp., photo taken in Singapore. Source.

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Above, stabilimenta of Argiope sp. take different shapes including circular and cross-shaped. Photo from Wikipedia.

What are the functions of the stabilimentum?

Various theories have been propounded as to the effect of the stabilimentum: strengthening the web, preserving the web by causing birds to avoid it, even attracting insects (although it would be natural to think that the more solid-looking stabilimentum might make the webs easier for insects to avoid). The spider we saw makes it into a “decorated” hiding place, but that is most likely an embellishment by this one species upon a structure originally serving other purposes.

In 1998 I-Min Tso, now a professor at Tunghai University in Taiwan, did a field study with Cyclosa conica (the spider we photographed) to find out whether “Stabilimentum-Decorated Webs Spun by Cyclosa Conica (Araneae, Araneidae) Trapped more Insects than Undecorated Webs”. He was able to make the comparison because where he worked (near Pellston, MI), the spiders sometimes omitted the stabilimentum (and 18 out of 24 webs with stabilimenta had no prey included in the “decoration”). This seems odd, as the stabilimentum with prey is cited as a characteristic of the genus Cyclosa, but maybe other observers have failed to notice instances of C. conica webs that lack the stabilimenta, or lack the wrapped prey within them. At any rate, Dr. Tso found that webs with stabilimenta caught more prey than plain webs even when the plain ones were larger. Similar results have been found for other species that add stabilimenta to their webs.

How might this work? At least one species, Argiope argentata (one of the Argiope spp. known as the “Writing Spider”), is said to spin special UV-reflecting silk for the stabilimentum. Theoretically this makes it more visible to insects, like the UV patterns on flowers, which tend to be “bull’s-eyes” surrounding the center where pollination takes place. In a laboratory where the light could be manipulated to contain UV radiation or not, fewer fruit flies flew to webs when the UV light was not present (webs were those of juvenile Argiope versicolor).

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Seen in UV, these flowers have a wide black “target”. Photo by Tom Blegalski/TTBphoto, from geneticarchaeology.com.

Under that theory, insects would fly toward the attractive UV center of the web (the stabilimentum) and not see the less-visible “this is a spider web!” part until too late. The theory fits the Writing spider, which prefers open sunny areas, better than our C. conica, which lives in sun-and-shade forests.

But the theory may be too good to be true, given that we don’t actually know enough about insect vision and behavior, and there is even disagreement regarding how UV-reflective spider silk is. In the real world, light conditions vary from place to place and moment to moment, even as a breeze changes the orientation of a web slightly, making it difficult to assign easy labels like more visible/less visible. And the visual systems of insects vary, with many being (I venture to say) unknown. The Australian spider Argiope aetherea was found to adjust “the quantity of silk decoration… adding more silk decoration when the web was located in dim light rather than bright light.” The authors of this study cite their findings as evidence that is “[c}onsistent with the prey-attracting function”, but of course it would also be consistent with any other function that involved visual perception even without UV involvement, e.g. signaling birds to avoid the web.

As a non-scientist, I’ve probably taken this topic far enough; the visibility and function of web decorations have been argued over for a hundred years, and modern technology seems merely to guarantee that each investigator with a spectrophotometer reaches a different conclusion from the others. One article (1), in 2005, summarizes areas of difference and ambiguity, ending with a possible redirection of emphasis: “The contrast of web decorations is consistent between families and different decoration patterns, raising the exciting possibility that their shape rather than spectral properties might explain variation in receiver response.” But there’s a review of the evidence in a long article not available online (2, abstract only), and now that my curiosity is up, I’m seeking a reprint of it.

1. Bruce, Matthew J, and Astrid M Heiling and Marie E Herberstein. 2005. Spider signals: are web decorations visible to birds and bees? Biology Letters 22 September 2005. 1 (3): 299-302.

2. Herberstein, M. E. , C. L. Craig, J. A. Coddington and M. A. Elgar. 2000. The functional significance of silk decorations of orb-web spiders: a critical review of the empirical evidence. Biological Reviews of the Cambridge Philosophical Society. 75 : 649-669. [abstract]

More photos and information about Cyclosa conica

eurospiders – good photos including extreme closeups of body parts

Range map

Cyclosa is derived from the Greek “kyclos” meaning “round” possibly with reference to its orb-web. Conica refers to the conical shape of the abdomen.

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Form and function: a columbine flower

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Like all columbines, the Western red columbine (Aquilegia formosa) above has a five-petalled flower with unusual “spurs” or tubules on the top. Each spur is formed by one of the five petals, curling into a cylinder as it rises.

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The lower ends of the petals join into a circle, within which are the yellow, pollen-bearing, stamens which extend beyond the petals. [Diagram below from USFS.]

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The sepals (that wrap the immature flower) are not green as in most flowers but red, and extend out at right angles when the flower opens.

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Western red columbine bud.

Flower design is all about getting pollen from the stamens to the pistils (female organs); form definitely follows function.What, then, has led to the development of these seemingly superfluous spurs? One clue is that they are of widely varying lengths. North American columbines range in spur length from from 7.5 to 123 mm (0.35 to 4.8 in.). And, because the first columbine—bearing a flower with short spurs— reached North America via the Bering Strait land bridge, between 10,000 and 40,000 years ago, all this change has taken place in a relatively short time, indicating some big payoff for the plant, in terms of survival or reproduction.

The columbine has both male and female parts in each flower, allowing for self-pollination, but that would not introduce any genetic variation. So the flower of the columbine is an elaborate package which has evolved to get effective pollination from its principal pollinators: bees, hummingbirds, and hawkmoths. And the spurs are an integral part of the process…

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because the knob at the end of each spur contains nectar, and that is a big attraction to pollinators.

The flowers and pollinators have conflicting interests: the visitor just wants the nectar, as much as it can drink, while the flower wants to dole out the nectar bit by bit in order to keep attracting more insects (or other pollinators—bats, birds). One method is by placing the nectar at the end of a passage just barely long enough for the tongue of the pollinators. They can sip but not slurp, and while forcing their way in they make good contact with the pistils and stamens to pick up and deposit pollen.

Darwin was intrigued by an extreme example, a Malagasy orchid which puts its nectar at the end of a 30 cm (11.8 in.) tube, and he hypothesized that flowers and their pollinators evolved together gradually in this regard. The flowers raised the bar, so to speak, a little at a time by lengthening the reach for the nectar, and the pollinating insects gradually evolved longer and longer tongues. In columbines, there are some species with short spurs accessible to bees, others with longer spurs that are mainly pollinated by hummingbirds, and some with even longer spurs for the long-tongued hawkmoth.

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Bee approaching flower, with tongue out. The long tan objects are pollen-bearing anthers, on the ends of the stamens. Photo.

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Hummingbird tongue. Photo.

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A giant hawk moth (Eumorpha typhon) adult with its tongue (proboscis) extended. Image by Alfred University artist Joseph Scheer.

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Photo by Gary Monroe.

Above is the flower of Aquilegia longissima (the longspur columbine of the SW US), which has the longest spurs of any species of columbine. Compare to those on the previous photos of our Western red columbine. The Western red is pollinated primarily by hummingbirds, though it attracts other insects too including bees and butterflies.

In a complex genetic study of North American columbine species published in 2007 (1), Whittall and Hodges found evidence that the ancestral short-spurred columbines had been bee-pollinated, but as they moved south and encountered first hummingbirds, then hawkmoths, had undergone two relatively quick transitions of lengthening spurs to adapt to these new pollinators.When long-tongued pollinators get nectar from a short-spurred flower, they will not need to shoulder their way in, and so won’t contact the stamens and pistils as much. They won’t pick up, or deposit, as much pollen.

And this led to development of different species of columbine. Once flowers in a certain area have gotten longer spurs, so that they mostly depend on a new longer-tongued pollinator, flowers that attract that particular organism better will be more successfully pollinated and produce more seeds. This may mean a change in color, flower orientation (facing up or down), or changes in form. Hodges subsequently studied color preference in the pollinators of columbines:

”What is important in this research is that hawkmoths mostly visit— and pollinate — white or pale flowers,” said senior author Scott A. Hodges, professor of ecology, evolution and marine biology at UCSB. “We have shown experimentally that hawkmoths prefer these paler colors.” When a plant population shifts from being predominantly hummingbird-pollinated where flowers are red, to hawkmoth-pollinated, natural selection works to change the flower color to white or yellow, he explained. [full original article here(2)]

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Photo by SA Hodges, MA Hodges, D Inouye.

This can even be seen in varieties of the same species, as in the case of Aquilegia coerulea, the Colorado blue columbine. Each of the three below is, according to the USDA, the same variety: A. coerulea James.

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Photo from USDA.

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Photo from USDA.

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Photo from USDA.

Here’s the process by which the flowers get lighter in color, as the latitude changes.

Aquilegia coerulea (Colorado blue columbine) ranges in color from dark blue to pale blue to white. Aquilegia coerulea is the southern most (northern New Mexico) occurring dark blue flowered columbine and it occurs at high elevations where colder temperatures generally preclude hawk moths. As Aquilegia coerulea expanded out of the Rocky Mountains into lower elevations and warmer temperatures, the species developed into white or very pale blue varieties. This change to a lighter coloration co-evolved, as hawk moths were available as an alternative pollinator to bees and bumblebees. It is also interesting to note that the spurs on the dark blue Aquilegia coerulea are short, similar to the other dark blue, high elevation columbines whereas the spurs on the pale blue to white Aquilegia coerulea are longer. (USFS)

In this theoretically orderly process whereby bees are excluded from the nectar supplies of long-spurred flowers, it happens that the bees sometimes choose to solve the problem in a “cutting the Gordian knot” fashion, by making holes in the spurs to drink the nectar directly. Unlike a bee who blunders around in the flower and departs with no nectar, the spur-cutting bee contributes nothing to pollination. But bees require both nectar and pollen, and the columbine’s pistils and stamens are easy to reach; so the bee who stops for a quick cheating drink may look in for pollen another time, thus fulfilling the needs of the flower as well as her own. (In honeybees the workers are all females.)

So it seems that Darwin’s idea of a gradual process, with increases in spur length being answered by longer tongues on the pollinator species, is not correct for columbines at least. Based on genetic data, Whittall and Hodges hypothesize a start-and-stop process: the columbines moved into new areas, with new longer-tongued pollinators (e.g. hummingbirds) which could raid the nectar without touching the pollen, and so flowers with longer nectar spurs became more likely to be pollinated and set seed. Instead of the flowers leading the dance by lengthening the spurs, it was the presence of different pollinators that forced change.

But Darwin was proved right in his prediction that an insect would turn up, capable of pollinating the incredibly long-tubed orchid. It’s a hawkmoth called Xanthopan morgani, or Morgan’s Sphinx, and here is its picture.

Morgan's sphinx.jpg

Photo from Wikipedia.

More images of these remarkable moths: night-time photo of Arizona moth feeding on Jimsonweed, showing tongue curled up in the air; pictures of the rare British hummingbird hawk-moth, which can hover: A, B; and photos of the African convolvulus hawkmoth.

References

(1) 2007: Whittall Justen B; Hodges Scott A. Pollinator shifts drive increasingly long nectar spurs in columbine flowers. Nature 2007;447(7145):706-9.

(2) 2009: Hodges, Scott A.; Derieg, Nathan J. Adaptive radiations: From field to genomic studies. Proceedings of the National Academy of Sciences June 16, 2009; 106 (suppl. 1): 9947–9954.

Attack of the mourning cloak butterfly larvae

That title sounds contradictory, doesn’t it? Butterflies are beautiful, innocuous, always to be protected. If only the world were as Walt Disney told us it was! [NOTE: I’ve learned from readers of this post that this caterpillar has a toxic substance in its hairs or spines that can cause a very painful reaction if you touch it, so be careful—indeed of any hairy or spiny caterpillar. See below,  https://nosleepingdogs.wordpress.com/2010/06/01/attack-of-the-mourning-cloak-butterfly-larvae/#comment-40639  and https://nosleepingdogs.wordpress.com/2010/06/01/attack-of-the-mourning-cloak-butterfly-larvae/#comment-40872 ]

The first title of this post was “Attack of the tent caterpillars”, because of what I saw. First the caterpillars,

TentCaterpillar3Damage2.jpg

then their “tent”. The black balls visible are probably frass (caterpillar excrement). A few caterpillars are under the tent; some species retire periodically to their tent for protection from the elements and birds.

TentCaterpillar3Tent.jpg

The closer I looked the uglier they were to me.

TentCaterpillarsStem.jpg

They were chowing down on the leaves of our little grove of aspens, planted a few years ago and much cherished.

TentCaterpillarAlders.jpg

Birds, including 6 pairs of nesting tree swallows (Tachycineta bicolor), usually keep insect pests under control around our house. But nobody showed any interest in this concentration of food on the aspens; too spiky, or maybe bad-tasting. Caterpillars eat so much so fast, they can defoliate trees. I went looking for something to spray them with and found we had no insect spray. Finally I used 409 cleaning spray, it certainly smells toxic. The next day most of the caterpillars were still alive and eating. Finally a better idea occurred: cut off the branches they were on and bag them up. Since the infestation had spread to just 3 branches, I was able to do that.

It was only afterwards that I succeeded in identifying the caterpillars. I had looked at all the so-called “tent caterpillars”, and others, without finding anything that matched. Then there they were: they would have grown up to be mourning cloak butterflies (Nymphalis antiopa).

MourningCloak.jpg

Photo from milesizz on flickr.

You can imagine how bad I felt. I’ve since thought that maybe I could have cut the branches and then lodged them in among the branches of some other tree. Or kept some and fed them until they pupated. The favored food trees for the larvae are elm, willow, hackberry, and trees of the genus Populus: cottonwood, poplar, birch, and, yes, aspen. Except for occasional cottonwoods and shrubby willow along the river, none of these are native around here. But we do see the occasional mourning cloak, one of which must have laid the eggs earlier this spring—this species overwinters as adults, emerges to mate and lay eggs in spring, then after 10 days or so the caterpillars hatch out, eat, pupate and emerge as butterflies before fall. Given how much caterpillars eat, harvesting enough willow from the riverbanks to keep them fed doesn’t sound practical, at least not for very many individuals. But if there is a next time I think I will try it.

Here are a few closeups of the caterpillars. Identification was hard, maybe because they go through 5 “instars” or stages, shedding their skins each time and so perhaps different instars look a bit different. Some of the photos of this species showed much hairier-looking caterpillars, whereas the ones here were extremely spiny but with few hairs.

TentCaterpillarCloseup1.jpg

TentCaterpillarCloseup.jpg

Note the red dots on the back, and the red legs (arrows).

CaterpillarLegs.jpg

The eggs would have looked like this.

MourningCloakEggs.jpg

Photo from Canadian Biodiversity Information Facility. For an excellent series of photos showing a female laying eggs, changes in the eggs as they get close to hatching, and the tiny new caterpillars, see this backyardnature.com page by Bea Laporte.

And each spiky black voracious caterpillar, after eating its fill of the tender leaves of our aspens, would have toddled off to some sheltered place to pupate, making a chrysalis like this.

Mourning Cloak Chrysalis2.jpg

Photo from bugwood.org.

Since mourning cloak adults overwinter, they are one of the earliest butterflies to appear, and regarded as a sign of spring. The “mourning cloak” refers to their dominant wing color, dark rusty red bordered with black—though it’s lightened with blue jewels and cream-colored edges.

MourningCloack4.jpg

I’ll close this tale of butterflies-never-to-be, with a melancholy ballad in which the mourning cloak appears, perhaps in the role of one of the Greek Furies, haunting one who has done wrong. Usually such messengers of vengeance and doom have unpleasant appearances, as did the Furies, but to the guilty heart a bright butterfly might be even more menacing than a dark spiky caterpillar.

The Mourning Cloak
(Karah Stokes/Spruce and Maple Music 1)

One fair morning late in June
The sun shone on the daisies white
When a messenger of sorrow deep
Came into my garden bright

Wings of deepest velvet black
Bound with gold and sapphires rare
A butterfly, a Mourning Cloak,
Like one a wealthy widow’d wear

He promised me a golden ring
But he gave it to a rich man’s child
He craved the ease wealth would bring
Above a love both true and wild

So I called him to our trysting place
“Since there’s no help, let’s kiss and part”
He took me in a sweet embrace
And he felt a penknife in his heart

He looked at me with fading eyes
I left him there as he left me
The dawn next morning brought the news
That he’d been set upon by thieves

Oh, butterfly, why do you haunt?
Know you the secret in my breast?
I pierced his heart as he pierced mine
I slew the one I loved the best

One fair morning late in June
The sun shone on the daisies white
When a messenger of sorrow deep
Came into my garden bright

swoosh.jpg