July 2016 – My Chicago Botanic Garden

The Birds, the Bees, and the Butterflies: Butterfly Mating Behaviors

On a typical day in the Butterflies & Blooms exhibition, you will see our butterflies flying, sunning themselves, or resting in the foliage.

If you happen to come to the exhibition just after a rain shower, and the sun is shining, it’s your lucky day, because love is literally in the air.

PHOTO: Butterflies mating. — Warm temperatures after a good rain seem to encourage butterfly mating. Photo © Andreas Krappweis

I remember one day in the exhibition when the weather was lousy. It had been raining all morning. While the volunteers and I huddled around in our ponchos, the butterflies were fine, hanging out in the trees, awaiting the sun. Around noon, the rain finally stopped and the clouds parted, saturating the exhibition with hot, bright sunshine. The exhibition had become a steamy hothouse. At that moment, almost every one of our 200-plus butterflies started flying. They had been waiting all morning for this.

The air in the exhibition was laced with pheromones from many different butterfly species, driving the males into a frenzy. I looked around and watched as male butterflies slammed into one another as they were in hot pursuit of a lone female. Even when two butterflies paired off, there would be a jilted male who wouldn’t give up trying to separate them by trying to knock the pair apart.

I was stunned at the variety and complexity of the courtship dances and rituals being displayed. A pair of Junonia iphita, or chocolate pansy butterflies, would fly to about 5 feet, at which point they would descend in a perfect interlocking spiral, straight down until they hit the ground. They would repeat this courtship ritual over and over again. Another incredible display was the Graphium agamemnon, or tailed jay butterfly.

PHOTO: Graphium agamemnon (Tailed jay) butterfly by Anne Belmont. — Tailed jay (*Graphium agamemnon*) butterfly by Anne Belmont

One tailed jay would fly in a straight line, while a second one (assumedly the male) would rapidly orbit around the first one, sort of like the moon orbiting the earth as it flies through space. This little trick just blew me away. I then noticed butterflies were mating in mid-air. One butterfly would do the flying, while the other would be hanging precariously below. This stunt was made possible by the male’s “claspers.” These claspers work exactly as they sound: they grab hold of the female, making sure that they remain together.

Papilio lowii (Great yellow mormon) butterfly by Anne Belmont. — Great yellow mormon (*Papilio lowi*) butterfly by Anne Belmont

PHOTO: Cethosia cyane (Leopard lacewing) butterfly. — Leopard lacewing (*Cethosia cyane*) butterfly by Robin Carlson

There were many more amazing acts of nature going on during this incredible spectacle. Some butterflies would attempt to mate with a different species. Sometimes males would try to mate. I even spied a trio of butterflies interlocked, forming a tangle of wings pointing in every direction. Two were a pair of Papilio lowii, or yellow mormon butterflies, while the interloper was a Cethosia cyane, or leopard lacewing. Now I thought I had seen it all. These butterflies were making human relationships seem tame. Visitors were enjoying the show, too. They would say, “This is supposed to be a ‘family’ exhibit!”

Females who had already mated or just weren’t impressed by the males would sit on a leaf with their wings spread and their abdomens held high in the air. This made mating impossible.

Blue Morpho (Morpho peleides) — Blue Morpho (*Morpho peleides*) by Bill Bishoff

Then, I saw something really baffling. To this day, lepidopterists know very little about the courtship of everyone’s favorite butterfly, Morpho peleides, the blue morpho. It started when one blue morpho clung to the netting of our enclosure.

Next, almost a dozen other morphos came over and began to form a very tight swarm around the morpho hanging on the netting. The group formed a writhing cloud around the butterfly on the netting, bumping into each other and circling around the individual. I did not see any of them pair off and mate. They just danced frenetically around the center morpho.

Was the center morpho somehow the only female, and all the males were simply trying to mate with her? I doubt it. We usually have an even ratio of males to females in the exhibition. Perhaps the center morpho acted as a beacon, releasing pheromones so that her kind would gravitate toward her designated “mating area” and mate with one another. She was the orchestrator of the ritual, silently sitting and directing her kin to carry out their biological imperative.

PHOTO: Large tiger longwing (Lycorea cleobaea) butterflies mating in the exhibit — Large tiger longwing (*Lycorea cleobaea*) butterflies mating in the exhibit; photo by Jill Emas Davis

The moral of the story is this: run to the butterfly exhibition if it has recently stopped raining. You might get a chance to see some amazing butterfly mating behavior.

Butterflies & Blooms is open daily, 10 a.m. to 5 p.m. through September 5, 2016. Bringing the family? Our Summer Family Fun Pack includes parking and five tickets to Butterflies & Blooms and the Model Railroad Garden.

Moth Pollinators and Hungry Caterpillars

To most people, the word “pollinator” is synonymous with the word “bee,” but only a fraction of plants are pollinated by bees.

In fact, many different insects and mammals are pollinators—bats, birds, beetles, moths, and more. As part of National Moth Week, we wanted to highlight our work on a very special group of moths: the Sphingidae, or hawkmoths, which pollinate more than 106 plant species in North America alone, and many more around the world.

PHOTO: A newly emerged Hyles lineata hawkmoth. — A newly emerged *Hyles lineata* hawkmoth

I am a research tech in the Skogen lab. I work with Krissa Skogen, Ph.D., her postdocs Tania Jogesh and Rick Overson, and fellow Garden scientist Jeremie Fant, Ph.D., on a National Science Foundation Dimensions of Biodiversity project entitled, “Landscapes of Linalool: Scent-Mediated Diversification of Flowers and Moths across Western North America.” Our project looks at floral scent and pollination in the evening primrose (Onagraceae) family.

Many species in the evening primrose family are pollinated by the white-lined hawkmoth (Hyles lineata). This pollinator is also an important herbivore! Female moths lay eggs on evening primroses, and their hungry caterpillars feed on the leaves, buds, and flowers. How does scent play a role in attracting hawkmoths? Do moths use it for pollination? Or do they use it to find host plants to lay their eggs? Or maybe both?

PHOTO: Hawkmoth pupae (Hyles lineata). — Hawkmoth pupae *(Hyles lineata)*

PHOTO: Hyles lineata eggs on an Oenothera harringtonii plant. — *Hyles lineata* eggs on an *Oenothera harringtonii* plant

From Dr. Skogen’s prior research, we know that floral scent can vary within and between plant populations. For instance, within the species O. harringtonii, some populations produce a scent compound called linalool while others do not. We think that the plants face a signaling dilemma: How do they use floral scent to invite their pollinators and yet avoid getting eaten? If female moths use linalool to lay eggs, then perhaps, in some populations, the plants benefit from not advertising their scent. To test this idea, we needed to conduct behavioral experiments to understand how Hyles perceive floral scent

This summer, along with Victoria Luizzi, a summer REU student from Amherst College, we looked at which plants female moths prefer to lay their eggs on—plants from populations containing linalool, or plants from populations without linalool. To answer this question, we first went to Colorado (where the plants naturally grow) and got plants from two different populations, one population that we know produces linalool and another we know doesn’t. Meanwhile our collaborator, Rob Raguso at Cornell University, sent us hawkmoth pupae and we patiently waited for them to emerge.

PHOTO: Victoria Luizzi (left) and Andrea Gruver (right) dissect a female moth to count remaining eggs. — Victoria Luizzi (left) and Andrea Gruver (right) dissect a female moth to count remaining eggs.

When the moths emerged they were placed in mating cages. Once mating occurred, females were transferred to a quonset in the evening that contained four plants from the linalool population and four plants from the non-linalool population. The moths were left overnight so the females had plenty of time to choose where they wanted to lay their eggs. The next morning, Victoria counted the eggs on each plant (which was sometimes hundreds!) to see on which plants the females were choosing to lay their eggs. In addition, we dissected each moth to see how many eggs the female did not lay.

PHOTO: Krissa Skogen moves a moth to its new enclosure in her office. — Krissa Skogen moves a moth to its new enclosure in her office

Over the course of the project, 12 females were flown in the quonset. Overall, the moths showed a preference for plants from the population that produces linalool. These data suggest that plants risk inviting foes while advertising to their friends—but we’ll need to collect a lot more data to be certain. Ultimately, both the insects that pollinate flowers as well as the insects that eat them might determine how a flower smells! We hope to continue this study to test our hypothesis further and learn more about how scent influences hawkmoth behavior, and how hawkmoth behavior influences floral scent and other floral traits of the plants they pollinate.

Studying the cryptic and beautiful Mompha moths

Most butterflies and moths featured in popular magazines and other media are large, well-known species, such as monarchs and luna moths.

Within scientific communities as well, species descriptions are biased toward larger moths, overlooking the multitude of tiny ones. Despite this tendency to favor larger species, the average moth is actually quite small, though far from nondescript!

PHOTO: Mompha species moth; photo taken in Utah. — *Mompha* species moth; photo taken in Utah

My research at the Chicago Botanic Garden focuses on an insufficiently studied moth group called Mompha, the largest genus within the family Momphidae. Mompha are tiny moths characterized by 4- to 8-millimeter tufted forewings and distinct color patterns.

PHOTO: Mompha stellella and M. eloisella moths — Specimens up close: *Mompha stellella* on the left and *Mompha eloisella* on the right. Both are found in Illinois, typically during the month of August. Photo credit: Terry Harrison

In North America, there are approximately 40 described species, or taxa, of Mompha. In addition to these identified species, a number of undescribed taxa are located throughout the North American West and Southwest. Mompha larvae feed on the reproductive (i.e., flowers, buds, and fruits) and vegetative (i.e., leaves, stems, and roots) structures of members of the Lythraceae, Cistaceae, Rubiaceae, and, most commonly, Onagraceae (evening primroses). In Illinois, Mompha can be collected in your backyard from Oenothera biennis (common evening primrose).

PHOTO: Mompha feeding and caterpillars. — Examples of *Mompha* bud-feeding and *Mompha* fruit-feeding caterpillars

Because many Mompha species share the same coloration, the only morphological characteristics—size, shape, and structure of an organism or one of its parts—that accurately differentiate taxa are unique genitalia. Experienced lepidopterists—butterfly and moth researchers or collectors—are able to carefully dissect moths in order to view their genitalia. However, due to the unique skills involved in moth dissection and genitalia identification, few scientists are qualified to identify different Mompha species.

PHOTO: Closeup of Mompha species caterpillar. — Close-up of *Mompha* species caterpillar

Instead of conducting genitalia dissections, I am sequencing six genes from hundreds of Mompha collected over the span of three years from the Western and Southwestern United States. DNA, like morphological characteristics, can be used to identify and characterize differences between species. To analyze the differences within Mompha DNA, I modeled phylogenetic trees.

PHOTO: Tubes of moth DNA samples. — Tubes and tubes of *Mompha* moth DNA samples

Phylogenetic trees depict evolutionary relationships between species in regard to genetic characteristic; closely related species share similar DNA and are thus placed close together on a phylogenetic tree. These trees will allow me to describe the natural history of Mompha in North America. This means that I will be able to identify new Mompha species, as well as Mompha host plant preferences, plant structure preferences, emergence times, and geographic isolation.

Check back here in a couple of months to read about the results of my analyses!

Select photos by Donald Hobern (Flickr: Mompha epilobiella) [CC BY 2.0], via Wikimedia Commons, and Rick Overson.
©2016 Chicago Botanic Garden and my.chicagobotanic.org

The Nocturnal Nuance of Moths

With more than 1,850 known species of moths in the state of Illinois—more than ten times the diversity of butterflies—it is a real adventure sampling the moth species inhabiting the McDonald Woods at the Chicago Botanic Garden.

Using a combination of light and bait traps along with visual searches, I have been investigating the diversity of moth species found in the restored portions of our oak woodland. Moths are removed from the traps and then photographed before being released back to the woodland.

PHOTO: Ctenucha virginica (Virginia Ctenucha) moth. — The metallic scales of *Ctenucha virginica* (Virginia Ctenucha moth) are striking—even its wings have a metallic sheen.

My interest in moths stems from the fact that many of the species are dependent on one or just a few native plant species for their survival, and as a result, may serve as valuable indicators of the health of our recovering, once-degraded oak woodland. The larval stages—the caterpillars—primarily feed on the roots, stems, and leaves of the plants. Adult moth species are very important pollinators. White-flowered and night-fragrant plant species are often what they seek. There are day-flying moths also, like some of the hawk moths (which are often mistaken for hummingbirds) that are seen visiting a variety of flowers in full daylight. Moths are also a tremendously important part of the food chain. Entomologist Doug Tallamy tabulated the number of caterpillars that were utilized to support one nest of black-capped chickadees and found that they consumed between 6,000 and 9,000 caterpillars, most of which were moth species. Adding even a few native plant species to your yard can benefit a multitude of these valuable invertebrates.

PHOTO: Smerinthus jamaicensis (Twin-spotted sphinx moth). — *Smerinthus jamaicensis* (Twin-spotted sphinx moth)

PHOTO: Plusia contexta (Connected looper moth). — *Plusia contexta* (Connected looper moth)

PHOTO: Ponometia erastrioides (Small bird-dropping moth). — *Ponometia erastrioides* (Small bird-dropping moth)

PHOTO: Plagodis phlogosaria (Straight-lined Plagodis moth). — *Plagodis phlogosaria* (Straight-lined Plagodis moth)

It is a never-ending surprise to see what new species will show up each time traps are placed.

Some species are so small (usually referred to by lepidopterists as micromoths) that most people would pass them off as gnats or pesky flies. Some micromoths are only 3-4 millimeters long. One in particular I like to refer to as the “Nemo” moth, as in Finding Nemo. I gave this species that name because its colorful pattern reminds me of a clown fish.

PHOTO: A cryptically-colored Noctua pronuba (Large yellow underwing moth). — A cryptically colored *Noctua pronuba* (Large yellow underwing moth)

At the other end of the spectrum are the moth species that are quite large. The giant silkworm moths, like the luna and Cecropia moths, have a wingspan of more than 140 millimeters. Starting in mid-July and going through September, a group of medium to large moths known as underwing moths starts appearing in the woods. These delta-shaped species are usually very cryptically colored on their forewing and brightly and starkly colored on their hind wing. The cryptic forewing allows them to blend in with the tree trunks they are resting on; the hindwing only becomes visible when they spread their wings to fly. It is thought to be a distraction or scare tactic to foil predators.

Although there is a subtle nuance of shapes, colors, and textures that distinguish many species, there are also those that are in-your-face with shockingly bright colors, metallic ornamentation, stark patterns, and jagged ridges of scales—much like a mountain range on six legs—that never fail to impress me. The looper moths are one good example. Many have stigmas (distinctive white patches and scrolling) on the surface of the wing and spectacular assortments of peaks, crowns, and ridges of scales on the thorax and inner edges of the wings. The scale patterns most likely evolved to break up the silhouette of the moth to make it less visible. One of the hooded owlet moths has a tall patch of scales on its thorax that looks like a witches hat when erect, but it can also be laid down over the moths head to make it look like a broken-off stick.

PHOTO: Leucania pseudargyria (False wainscot moth). — *Leucania pseudargyria* (False wainscot moth)

In general, there is a new group of species that emerges about every two weeks during the year, with midsummer being the peak for species and abundance. Many moth species have relatively short flight periods and can only be seen at certain times of the year, but some have multiple broods that show up several times during the year. When I show some of these moths to colleagues, they almost always say, “I never knew these things existed.”

Under the cover of darkness, there is a world of beauty and fascination fluttering silently among the trees. It makes me wonder if the full moon doesn’t show up once a month just to shed a little light on the show, just so we don’t miss it completely.

Studying in an amazing, open-air encyclopedia

I am an enthusiast of space design.

After a two-year technical degree at École Boulle (a school of fine arts and crafts and applied arts in Paris, France), I decided to study for my master’s degree at the National School of Landscape Architecture of Versailles.

PHOTO: French summer intern Lisa Ho. — I spent most of my time working and learning in the Regenstein Fruit & Vegetable Garden.

For me, work in landscape architecture is the best way to unite many different and interesting fields, such as art, sociology, and ecology. Designing spaces where people will live and have an emotional connection to their surroundings is my way of creating happiness.

I chose to do an internship in the United States to broaden my understanding of how cities here developed over time in comparison with France, which has had many hundreds of years to develop. In Chicago, I saw that the gardens were designed like the links of the city, and learned one of the reasons for this is Chicago’s motto, Urbs in horto, which means “city in a garden.”

Through my internship at the Chicago Botanic Garden, I also wanted to learn practical horticulture skills, like plant identification, choosing the right plants for certain spaces, and techniques for good plant health. For example, to improve air circulation and the growth of some vegetables, I learned to stake up tomatillos, and use trellises for beans.

PHOTO: Lisa Ho's sketchbook illustrations and notes on plantings in the vegetable beds. — My sketchbook illustrations and notes on plantings in the vegetable beds. Three Sisters is a trio of vegetables planted together for their mutual benefit. Corn provides a natural pole for bean vines to climb. Beans fix nitrogen on their roots, improving the overall fertility of the soil. Squash vines shade emerging weeds and keep the soil moist.

I spent a total of four weeks at the Chicago Botanic Garden, working mainly in the Regenstein Fruit & Vegetable Garden under that garden’s horticulturist, Lisa Hilgenberg. During Pepper Sundays, I learned that one of the special plants in the Fruit & Vegetable Garden is the bull-nose pepper—a favorite of Thomas Jefferson, who was an ambassador to France and a great plant enthusiast. He made many plant exchanges with people around the world, especially France. It goes to show that plants everywhere bring people together, no matter the country or culture.

PHOTO: Lisa Hilgenberg, and Lisa Ho pose with Christine Moore from the United States National Landscape Arboretum in Washington DC. — Lisa Hilgenberg and Lisa Ho pose with Christine Moore from the United States National Arboretum in Washington, D.C. Moore is the curator of the National Herb Collection, and we were able to work together for several days.

Gardens are always changing, so there were always new things to see and learn each day—not just with the plants, but also with understanding how people use the gardens at the Chicago Botanic Garden.

Visitors come to learn about plants, to enjoy their day in a beautiful place, and to be inspired. I saw how important green spaces are to people. My internship has encouraged me to share knowledge with the visitors, the interns, the staff, and volunteers. It is a true collaboration and exchange between people. For example, when I worked in the nursery, the staff and the interns showed me the breadth of the production and how the Garden is constantly trying to help people experience the Garden in a new way.

For me, the Chicago Botanic Garden, in addition to being a beautiful garden, is an amazing, open-air encyclopedia of plants and garden design, as well as a wonderful space for public enjoyment.

I am grateful to the French Heritage Society, which partners with the Garden on a collaborative internship exchange, to the Ragdale Foundation, which has hosted me, and to the Chicago Botanic Garden and Lisa Hilgenberg for giving me this extraordinary opportunity. And finally, I hope that this will be the beginning of new friendships for me.

This is the fifth year of our wonderful intern exchange with the French Heritage Society. As Lisa Ho spent her summer in Chicago, Chicago Botanic Garden employee Eileen Brucato went over to France to gain experience in three chateau gardens: Château de Brécy, Château d’Acquigny in Normandy, and Château de la Bourdaisière in Tours.