Seeing Stripes: The Zebra Longwing Butterfly

The zebra longwing (Heliconius charithonia) is a common resident of the Cockrell Butterfly Center (CBC). This butterfly is easily recognizable with boldly striped yellow and black wings. When visiting the CBC, you’ll often spot them sipping nectar from the flowers and nectar feeders or sunning themselves with their wings spread open. These butterflies have some unique features and behaviors that set them apart form the rest!

Aposematic Coloration

Bright, contrasting warning colors are known as aposematic coloration. They indicate to potential predators of the “unprofitability” of a prey item. The bold yellow and black stripes on the zebra longwing serve as a warning signal to potential predators of the butterfly’s unpalatable and poisonous nature. Zebra longwing caterpillars feed on passion vine (passiflora) leaves and acquire some of their toxins, making them distasteful to predators. 


Bright, contrasting colors warn predators to stay away.

Pollen feeders

Most butterflies can only sip fluids with their proboscis, most commonly flower nectar. Zebra longwings, on the other hand, also feed on pollen. They use their saliva to dissolve the pollen and take in its nutrients. Pollen, unlike nectar, contains proteins and is very nutritious. Pollen feeding is correlated with overall higher fitness. This diet allows zebra longwings to live longer (up to six months) and increases females’ egg production. 

zebra pollen face

You can see pollen on this zebra longwing’s proboscis. Feeding on pollen increases longevity.

Pupal Mating

Male zebra longwings exhibit pupal mating, zebra_longwing_and_chrysaliin which they will mate with a female before and immediately after she emerges from her chrysalis. Males will seek out a female pupae and will perch on it and guard it from competing males. Many males may fight for the opportunity to mate with the yet-to-emerge female. The successful male will insert his abdomen into the softening pupae and copulate with the female. Mating will continue as she emerges and dries her wings. The males will pass a nutrient-rich spermatophore to the female which reduces her attractiveness to future mates. This male (at right) begins mating with the female before she has even emerged from her chrysalis.


This mating pair shows the freshly emerged female still clinging to her chrysalis.

Communal Roosting

Adult zebra longwings roost communally in groups of up to 60 individuals at night. They tend to return to the same roost on a nightly basis. In the late afternoon, zebras can be observed fluttering and basking near their roost site as they slowly gather together for the night. Roosting together provides protection from predators and retains warmth. 


These zebra longwings are preparing for the night by roosting together for safety.

So now you know! These beautiful, brightly colored butterflies are bad-tasting, and long-lived. They have unique mating habits and the snuggle together at night. Something to remember next time you visit the zebras at the CBC!

Being Natural: Nancy Greig

In 1994, Dr. Nancy Greig inherited what was “basically a hole in the ground.”

More than 21 years later, the Cockrell Butterfly Center is a world-renowned exhibition, and Greig’s vision is a major part of the success of both the CBC and the Houston Museum of Natural Science.

As Greig puts it, getting the job “was just lucky.” Before moving back to Texas, Greig was wrapping up a year of postdoctoral studies at the University of Missouri-St. Louis where she was, in her words, “changing caterpillar diapers.”

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Cockrell Butterfly Center Director Dr. Nancy Greig visits with a rice paper butterfly in the facility her efforts have made hugely popular.

“This professor I was working with was looking at the caterpillar fauna on three species of oak tree. After we collected them in the field it was my job to raise them in the lab so we could determine what species they were,” Greig said. “I had to get them fresh leaves and clean the containers out, so that’s why I called it changing caterpillar diapers. Pretty much you have to dump the ‘frass’ out every day.”

Greig’s background is a blend of tropical plant biology and entomology.  She did her graduate work at the University of Texas, Austin, conducting research in Costa Rican rainforests under the supervision of Dr. Larry Gilbert, who studies tropical butterflies.  Between receiving her Ph.D. and the postdoc position, Greig spent two more years in Costa Rica teaching a tropical ecology course, that was “like summer camp for graduate students – an amazing experience.”  She was back in Austin for a Christmas visit in 1993 when her UT advisor remembered he had recently received a call about a position at HMNS.

“I thought I was going to be a University professor or something, and I was expecting another year or two of postdocs,” Greig said. “But I got in touch with the museum and they wanted me to come to Houston for an interview. Two weeks later, they called in St. Louis and asked, ‘How fast can you be here?’”

Greig’s field experience in Costa Rica gave her a leg up on the job; during her field work and subsequent teaching, she had spent plenty of time getting intimately familiar with the neotropical rainforest environment the museum wanted to craft in Houston.

When Greig first arrived in Houston, the Cockrell Butterfly Center was still under construction.

“It was a hard-hat zone,” she said. “There were cables and ropes everywhere. Some of the cement planters were in place, but not much else. The metal struts were up but there was no glass.


Greig educates students about plants as well as insects. In nature, the two forms of life depend on each other.

“It was so bare when we first opened, so of course it’s grown up [since then]. At first the plants were so small,” Greig said. But despite the bareness, “the first year, we had a millon people come through the butterfly center. It was a big deal, and kind of a trial by fire.  I had never been on television or radio before, and we got plenty of press. I had to learn to talk in front of a camera!”

Her first duties were to help oversee the construction and work with the builders and the landscape architects.  She also had to hire staff, get the butterfly importation permits, and create the museum’s first entomology hall. This precursor to the current Brown Hall of Entomology contained many preserved specimens but had lots of text and no interactive displays.

“People would go through the butterfly center first and then go up there – and the energy level just died,” Greig said. “There were some great specimens and some good information, but it was a very quiet, somber space.”

After several years, Greig and the Exhibits department began planning a bigger, brighter, vibrant entomology hall. Along with a couple of museum board members, they visited museums and zoos all over the country to see what others had accomplished and how to adapt the best qualities into one fun, educational hall. The result has been well-received.

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Greig educates a student on butterfly identification at the CBC.

Gone were the static displays, replaced by interactive games, giant models and live arthropods. One of the biggest changes was to move the display cases closer to the ground, making the whole exhibit more kid-friendly and engaging.

The unveiling of the brand new Brown Hall of Entomology on July 1, 2007 was one of the highlights of Greig’s 22-year tenure as director, followed closely by the hysteria of Lois the corpse flower and “Cash for Cockroaches.”

In preparation for the opening of the new exhibit in 2007, the CBC offered to buy up to 1,000 cockroaches for 25 cents each from Houston residents to fill a feature of the hall, the Roach Dome. The public response was huge, and the story made the front page of the Houston Chronicle before jumping nationally and beyond with coverage from Reuters.

Lois similarly brought in a surge of media attention when the giant corpse flower showed hints of blooming in the summer of 2010. After being cared for and nurtured for years up in the greenhouses, Lois sprouted a slightly different stalk, sending the city of Houston into a three-week frenzy that culminated with her stinky bloom in July. Celebrity status was afforded to horticulturist Zac Stayton, a parody Twitter account was born, t-shirts and buttons were mass produced, and a documentary was made and released in the aftermath.

“It was so great for the museum; so great for Houston,” Greig said. “That is what the museum should be about. It was exciting and educational and fun. There was one woman who came over 30 times! At least once, sometimes twice a day!”

While Greig has always loved “creepy crawlies,” she has devoted her life to educating others about the positives bugs and arthropods provide to the world. She says that you can’t force that appreciation on people, but you can try to get through to them by asking them to imagine what the world would be like without them, among other tactics.

“I try to educate them with some fun stories and show that I’m not afraid. That there’s nothing to be afraid of. Seeing that someone can be totally comfortable with insects and spiders is important,” Greig said.

Nancy Greig Cockroaches

As an arthropod-lover, Greig believes all insects are important, and that even roaches are deserving of our love.

Greig herself is very enthusiastic about the evolution of many insects and their various adaptations for survival. The camouflage used by insects such as walking sticks and katydids really gets visitors thinking about how life got to this point, and Greig counts that as one of the must-sees of the Cockrell Butterfly Center. She is passionate about moving past the “creepy crawly” label as a result.

“It’s neat to be able to use the butterflies as the hook, the ambassadors, I would say, to bring people in, and then we help them to realize that bees and even cockroaches are important,” Greig added.

While Greig has always had a love of nature, she arrived at UT from Calgary ready to study linguistics. She says she took a circuitous route back to biology and that she is proof that “you can do really whatever you want to do.”

“It’s turned out to be really a perfect fit,” Greig said. “Running the Butterfly Center has been a great job for me. There are really not that many jobs like this. It was total serendipity.”

Visitors to the Cockrell Butterfly Center in October can see special plant life in the rainforest conservatory during the temporary exhibition, Savage Garden. And teachers hoping to meet Greig can mark their calendars for The Educator Event @HMNS Jan. 23, 2016, where she will give the keynote address. In addition, educators can book one of Greig’s Bugs On Wheels Outreach Programs, Monarchs or The Buzz About Bees.


HMNS greenhouse teaches how to plant a butterfly oasis in your back yard

They float on the wind, decorate your back yard in the spring and summer, and inspire warm emotions with their delicate wings. They seem carefree, at home in any meadow, but butterflies have more specific needs than we might imagine.


Monarch butterflies don’t live just anywhere; they need habitat, too!

As urban sprawl continues to grow, reducing green space and native plant growth, natural butterfly habitats are shrinking. Butterflies require specific plants on which to feed and lay eggs. Caterpillars are finicky eaters.

Soni Holladay, Houston Museum of Natural Science Horticulturist and Greenhouse Manager, will lead a class Saturday, April 18, beginning at 9 a.m., to share information with the public about how best to plant a garden that will attract native butterfly species, creating a backyard butterfly nursery.

Holladay’s main concern is planting tropical milkweed to attract the famous migratory monarch butterfly. Though tropical milkweed is easier to grow, scientists have discovered it may play a part in declining monarch populations.

A parasitic species of protozoan called Ophryocystis elektroscirrha, or simply Oe, grows on the body of their monarch hosts. When infected monarchs land on milkweed to lay eggs, Oe spores slough off and are left behind. Caterpillars, which eat the milkweed, ingest the spores and become infected.

When the protozoans become too numerous, they can overwhelm and weaken individual butterflies, causing them to suffer. Several heavily infected monarch can take a toll on the local population. Oe can kill the insects in the larval or pupal stage, as well, before they can reach full adulthood.


Tropical milkweed survives the Houston winters, making them a perennial plant and a possible danger to monarch butterfly populations.

Native milkweeds die off every year and grow back in the spring Oe-free as part of their cycle, but the evergreen tropical milkweed remains standing year-round, providing a vector for the protozoan to spread.

“We’re advising everyone who plants tropical milkweed to cut it back once a year or more,” Holladay said. Much like their native cousins, the tropical variety will return later, a healthy habitat for butterflies.

Holladay’s class will offer more details about this and other butterfly-raising issues. After the class, guests will tour HMNS greenhouses and our on-site butterfly-rearing operation. Tickets $23, all ages. Native milkweed plants and other seeds will be available to get you started.

The Butterfly Center beat: Everything you ever wanted to know about raising Atlas moths


The Atlas moth (Attacus atlas) is a large moth belonging to the Saturniidae family. Saturniids, familiarly called giant silk moths, include some of the largest species of Lepidoptera (moths and butterflies). Two local species that may be familiar to readers are the polyphemus and luna moths.

Atlas moths are considered the largest moths in the world in terms of total wing surface area. Their wingspans are also among the largest, often reaching over 10 inches. They are strikingly beautiful, with tawny wings punctuated with translucent “windows” bordered by black. Their most distinguishing feature (other than their size) is an extension of their forewings that resembles a snake’s head, thought to be a means of scaring off potential predators.

The forewing of an Atlas moth resembles a snake’s head. ©Erikki Makkonen

The forewing of an Atlas moth resembles a snake’s head. ©Erikki Makkonen

These spectacular moths make superb additions to the Cockrell Butterfly Center. During the day, they spend most of their time motionless, clinging to the side of a tree or other surface. Visitors can thus get up close to intimately study these creatures, and can clearly observe their fat, furry bodies, fuzzy antennae, and teddy bear like expressions.

Close-up of the fuzzy face and feathery antennae of a female Atlas moth (males have larger antennae). © John Horstman

Close-up of the fuzzy face and feathery antennae of a female Atlas moth (males have larger antennae). © John Horstman

Once night falls, the male Atlas moths take flight in search of a female. The search has a sense of urgency, as adult Atlas moths typically live only about one week. This is because the adults do not have fully formed mouth parts and therefore cannot eat; they are sustained only by the fat reserves they built up as a caterpillar. The moths will quickly mate, lay eggs, and die soon after.

One day at the Cockrell Butterfly Center, a male and female emerged from their cocoons around the same time. We took the opportunity to breed and raise this species of moth. The newly emerged male and female were placed in a flight cage in the greenhouses on the top level of the museum parking garage. They paired the very first night they were together. During mating, the moths remained coupled for several hours. Then, over the next three days, the female laid approximately 150 crimson eggs, placing them indiscriminately along the walls and edges of the flight cage.

A mating pair of Atlas moths clinging to the sides of a flight cage. The larger of the two is the female.

A mating pair of Atlas moths clinging to the side of a flight cage. The larger of the two is the female.

Atlas moth larvae are generalists, meaning they will feed on a wide variety of host plants (but not all plants). Hoping to determine which of several possibilities would be the best food for our caterpillars, we searched the literature for recorded host plants.

We chose four that we had available, including Camphor Tree (Cinnamomum camphora), Vitex (Vitex trifolia purpurea), Mahogany Tree (Swietenia mahoganii) and Sweet Potato Vine (Ipomoea batatas). Gathering the eggs, we divided them among four plastic containers lined with moist paper towels and ventilated with tiny holes poked in the lid, each containing a different kind of leaves.

The eggs took 10 days to hatch. The hatchling larvae were covered in pale protuberances and had black heads. After eating their eggshell, the tiny caterpillars began eating the provided foliage. Once the caterpillars were feeding reliably, they were moved to netted cages containing potted plants, so the leaves would be constantly fresh.

The caterpillars hatched on a Friday in September. To track their weekly growth and development, we took a photograph of them each Friday thereafter. It quickly became obvious that the caterpillars on Camphor were thriving: they grew bigger and faster than their siblings on the other plants (the pictures shown below are of larvae fed on Camphor). In each photograph, larvae were placed next to a standard sized Popsicle stick, fondly known as “Size Reference Ralph,” to track their relative growth.

The caterpillars took six weeks from hatching to pupation. They ate voraciously, becoming soft and fleshy to the touch, and were a pale blue-green color. Their backs were covered in a Mohawk of tubercles with a thick, waxy, flaky coating. After six weeks, the caterpillars were almost as long as Size Reference Ralph and were quite pudgy.

The sequential pictures show the dramatic changes in the larvae, followed by the start of silk spinning, and finally a complete cocoon. Once they finished their cocoons, the larvae pupated inside. We then gently moved the dried cocoons to the emergence chamber inside the entomology hall of the Butterfly Center.

Egg to cocoon in Atlas Moths. Pictures were taken one week apart next to Size Reference Ralph. ( Pictures courtesy of Lauren Williamson)

Egg to cocoon in Atlas Moths. Pictures were taken one week apart next to Size Reference Ralph. (Pictures courtesy of Lauren Williamson)

Then we waited. Atlas moths may eclose from their cocoon in as little as three weeks, but can sometimes take several months. To escape from their silken enclosures, they must excrete a substance that dissolves a hole in the silk, allowing them to crawl out. They then cling to their cocoons while their wings expand and dry.

The first Atlas moth of our batch of cocoons emerged on Dec. 17, almost 3 months after hatching from the egg. It was a large female, with a wingspan of just over 10 inches. As you can see, Size Reference Ralph was dwarfed by her!

Our first Atlas Moth to emerge on Dec. 17th 2013. (picture courtesy of Lauren Williamson)

Our first Atlas moth to emerge on Dec. 17, 2013 (picture courtesy of Lauren Williamson).

Know a girl who’s interested in math and science? Come to GEMS (Girls Exploring Math & Science) on Sat., Feb. 8 from 9 a.m. to 1 p.m. The Museum will be filled with hands-on science and math for everyone to experience. Local professionals will be at the Museum to answer questions about their careers in the fields of science, technology, engineering and math.

The event is free with paid admission to the Museum. Click here for $7 admission to all permanent exhibit halls on Sat., Feb. 8.