Animal
Glasswing butterfly
The glasswing butterfly has see-through wings, like little windows! It lives in the forests of Mexico and Central America.
The glasswing butterfly has wings you can see right through, framed with orange-brown edges. It lives from Mexico to Panama, and its caterpillars eat plants called Cestrum. Scientists study its clear wings because they hardly reflect any light, which could help people design better glass.
Greta oto, an ithomiine (clearwing) butterfly of Mexico and Central America, has largely transparent wings whose membrane is covered with irregular wax nanopillars that cut reflection even at steep viewing angles. Its larvae feed on Cestrum (Solanaceae), and it is widely bred in Costa Rica for butterfly houses around the world.
Photo: Quartl, CC BY-SA 3.0, via Wikimedia Commons
Meet the glasswing butterfly
The glasswing butterfly has clear wings.
You can see leaves and flowers right through them! The edges of its wings are orange-brown, and it has a white stripe near the tip of each front wing.
Most butterfly wings are covered in tiny colored scales, like roof tiles. The glasswing butterfly is different: large parts of its wings are clear, like windows, so you can see right through them. The clear panels are framed by orange-brown and dark edges, and each forewing has a white bar near its black tip.
It is a small butterfly, with a wingspan of only about 56 to 58 millimeters, a little wider than a credit card is tall. Its scientific name is Greta oto.
Greta oto is a clearwing butterfly of the ithomiine group (Nymphalidae: Ithomiinae); Butterflies of America treats it as a subspecies, Greta morgane oto. In Costa Rica's Monteverde region, William Haber records a wingspan of 56 to 58 millimeters and a forewing length of 27 to 31 millimeters, and identifies the species by its broad black forewing apex and the strong white bar bordering it.
The wings of butterflies and moths are typically covered in thousands of flat, overlapping scales. In the glasswing's transparent regions, the scales are reduced to thin bristles, leaving the membrane exposed, while the opaque borders keep flat, round scales (Pomerantz and colleagues, 2021).
Quick facts
- Group
- Invertebrate
- Wingspan
- 5.6 to 5.8 cm
Where it lives
Glasswing butterflies live in Mexico and Central America.
They fly in warm forests, from low places up into the mountains.
The glasswing butterfly lives from Mexico south through Central America to Panama. In Costa Rica's Monteverde area it is common on the Pacific side, from the lowlands up to about 1,500 meters, and rare on the Atlantic side.
You might also see glasswings in butterfly houses far away, in Europe or North America. Those butterflies were raised by people, mostly in Costa Rica, and sent around the world as pupae. They do not live wild there.
Haber gives the species range as Mexico to Panama, and Butterflies of America as eastern Mexico to Panama, with Guatemala as the type locality (the place its first described specimens came from). In the Monteverde region of Costa Rica it is common on the Pacific slope from the lowlands to 1,500 meters and rare on the Atlantic slope down to 200 meters. GBIF holds scattered records further south, but the sources used here do not describe a native range beyond Panama, so none is shown.
Hall (1996) notes that G. oto is bred mainly in Costa Rica and exported as pupae to butterfly houses around the world, so captive glasswings are often seen far outside the native range.
Continent
Did you know?
You can see through a glasswing's wings.
Parts of a glasswing's wings are as clear as a window, because they have thin bristles instead of flat colored scales.
Transparent regions carry thin, bristle-like scales at low density, exposing the membrane (Pomerantz et al., 2021).
Where can you find this animal?
- Lives here naturally · Countries and seas named by a scientific source
- Sightings recorded · Records of wild sightings (GBIF)
Lives here naturally · Countries and seas named by a scientific source
Forests from Mexico to Panama, from lowlands up to about 1,500 meters. Haber gives the range as "Mexico to Panama" and Butterflies of America as eastern Mexico to Panama (first described from Guatemala), so the Central American countries in between are shaded; Belize and Honduras have no GBIF records. Butterfly-house glasswings elsewhere are captive, not wild.
Places: Mexico, Guatemala, Belize, Honduras, El Salvador, Nicaragua, Costa Rica and Panama.
Source: https://efg.cs.umb.edu/monteverde/But/Ithomid/Gre-oto.html · checked October 2026
Sightings recorded · Records of wild sightings (GBIF)
Counts of GBIF records of wild observations (human and machine) and preserved specimens. Records include introduced populations, vagrants, escaped or released animals and misidentifications, so a country with records is not necessarily part of the native range.
Wild sightings have been recorded in Mexico, Nicaragua, Costa Rica, Brazil, Panama, Colombia, Denmark and El Salvador.
Source: gbif · checked October 2026
Range maps show where scientists say an animal lives, often country by country. An animal may live in only part of a country shown, and sightings records can include animals that wandered far from home.
What it eats
Glasswing caterpillars eat the leaves of plants called Cestrum.
The grown-up butterflies sip sweet nectar from flowers through a long, curly tongue.
Glasswing caterpillars eat the leaves of Cestrum, a group of shrubs in the nightshade family. In the wild they have been found on several kinds, such as Cestrum lanatum and Cestrum standleyi.
Like other butterflies, adult glasswings drink liquid food, such as flower nectar, through a long tube called a proboscis. When they are not feeding, they keep it rolled up in a neat coil under the head, as you can see in our photo.
Larval host plants are species of Cestrum (Solanaceae). Wild records include C. standleyi and C. lanatum (Hall 1996, citing DeVries 1987 and others), and Haber lists C. lanatum, C. racemosum and an unidentified Cestrum at Monteverde. In captivity larvae use several Cestrum species, with C. nocturnum strongly preferred in one greenhouse study; larvae on some other species often died in the first instar or grew more slowly.
Adults feed through a coiled proboscis, visible in the photo, which unrolls to take liquid food such as nectar.
Did you know?
Many glasswings in butterfly houses come from Costa Rica.
Glasswings are bred mainly in Costa Rica and sent around the world as pupae to butterfly houses.
Hall (1996) reported that G. oto is bred mainly in Costa Rica and exported as pupae to butterfly houses worldwide.
Wings you can see through
Most butterfly wings are covered in tiny colored scales.
The glasswing's clear wings have only tiny hairs instead. They are smooth and hardly shine at all.
Why are the glasswing's wings clear? In the see-through parts, the usual flat scales are replaced by thin bristles, so you look straight through the thin wing skin. That skin is covered in tiny bumps and pillars, far too small to see, made partly of wax.
These pillars stop the wing from reflecting light like a mirror, even when you look at it from the side. Scientists found that their uneven sizes are the secret. Scientists think they could inspire new materials that cut glare.
The transparent regions show remarkably low haze and reflectance across the visible spectrum, even at view angles of 80 degrees (Siddique and colleagues, 2015). This omnidirectional anti-reflection comes from nanopillars on the wing membrane that, unlike other natural anti-reflective coatings, are irregularly arranged and vary randomly in height and width; simulations showed the random heights strongly reduce reflection.
Pomerantz and colleagues (2021) found two layers of nanostructure: regular nipple-like bumps below and irregular wax-based nanopillars of long-chain n-alkanes above. Chemically removing the wax pillars increased reflection, confirming their role. During development, transparent regions have fewer scale-forming cells, which grow thin, bristle-like scales.
Egg, caterpillar, pupa, butterfly
A glasswing starts as a tiny egg on a leaf.
A caterpillar hatches and eats Cestrum leaves. Then it becomes a pupa, and inside it changes into a butterfly. This big change is called metamorphosis.
Like all butterflies, the glasswing goes through complete metamorphosis. A female lays eggs on Cestrum plants. Each caterpillar eats and grows, then forms a pupa, also called a chrysalis. Inside the pupa its body is rebuilt, and an adult with see-through wings comes out.
In the wild, the young stages live alone rather than in groups. Butterfly farms in Costa Rica raise many glasswings and ship the pupae to butterfly houses around the world.
Development is holometabolous: egg, larva, pupa and adult. Eggs are laid on Cestrum hosts and, at Monteverde, the early stages are solitary (Haber). Hall (1996) described the life cycle of captive G. oto bred from Costa Rican stock in an English greenhouse, while noting that captive butterflies may behave differently from wild ones.
The transparency itself is set up in the pupa: in a developmental time series, Pomerantz and colleagues (2021) showed that scale precursor cells are less dense in future transparent regions, and that the cytoskeleton organizes differently as bristle-like and flat scales grow.
Hiding in plain sight
When a glasswing sits on a leaf, you can see the leaf through its wings.
Can you find one in a picture? Look for the orange edges and the white stripe! Glasswings are common in their forests.
When a glasswing rests, its clear wings let the background show through, and they hardly reflect any light. Only the orange-brown edges and the white bar stand out.
Glasswings are common in the forests where they live. In butterfly houses they fly, court and breed well, which is why so many people around the world have seen one up close.
At rest, the transparent panels let the background show through with very little reflection, leaving the opaque borders and white bar as the most visible parts. The opened sources describe the optics and development of the wings, not their effect on predators, so any defensive benefit is not covered here.
Haber lists G. oto as common at Monteverde. Hall (1996), observing marked individuals in a small English greenhouse, found that the species shows apparently natural courtship and breeds readily, and argued that captive populations are useful for behavioral research as well as exhibition.
Did you know?
Glasswing wings have tiny pillars made partly of wax.
The wings are covered with tiny wax pillars that stop them from shining like a mirror.
Wax-based nanopillars of long-chain n-alkanes form the upper anti-reflective layer; removing them chemically increases reflection.
A common butterfly with a big future
Glasswing butterflies are common in their forests.
People raise them on butterfly farms. Scientists copied their wings to make glass that hardly shines.
The glasswing butterfly is common in its forests, and it has not been assessed by the IUCN Red List. Butterfly farms in Costa Rica breed it and send the pupae to butterfly houses in other countries.
Its wings have inspired engineers. In 2019, researchers in Greece used laser pulses to make glass with tiny random pillars, copying the glasswing (and some cicadas), and it reflected less than 1 percent of light at many angles.
Greta oto has no IUCN Red List assessment, and Haber lists it as common at Monteverde. It is bred mainly in Costa Rica and exported as pupae to butterfly houses worldwide (Hall 1996).
Its nanostructures are a model for biomimetic materials. Siddique and colleagues (2015) showed that random pillar heights are key to omnidirectional anti-reflection, and Papadopoulos and colleagues (2019) used ultrashort laser pulses to texture glass with random nanopillars mimicking G. oto and cicada wings, reaching reflectivity below 1 percent at various angles in visible light.
Amazing facts
-
You can see through a glasswing's wings.
Parts of a glasswing's wings are as clear as a window, because they have thin bristles instead of flat colored scales.
Transparent regions carry thin, bristle-like scales at low density, exposing the membrane (Pomerantz et al., 2021).
-
Glasswing wings have tiny pillars made partly of wax.
The wings are covered with tiny wax pillars that stop them from shining like a mirror.
Wax-based nanopillars of long-chain n-alkanes form the upper anti-reflective layer; removing them chemically increases reflection.
-
Many glasswings in butterfly houses come from Costa Rica.
Glasswings are bred mainly in Costa Rica and sent around the world as pupae to butterfly houses.
Hall (1996) reported that G. oto is bred mainly in Costa Rica and exported as pupae to butterfly houses worldwide.
Words to know
- transparent
- clear enough to see through
- scales
- tiny flat plates that cover most butterfly wings and give them color
- proboscis
- a butterfly's long drinking tube, kept rolled up when not in use
- metamorphosis
- the big change in body shape from caterpillar to butterfly
- pupa
- the stage when a caterpillar changes into an adult; also called a chrysalis
- reflection
- light bouncing back off a surface, like a shine or glare
Discovery challenge
-
What is special about a glasswing's wings?
What makes the glasswing butterfly's wings special?
What is the notable optical feature of Greta oto wings?
- You can see through them
- They glow in the dark
- They are made of feathers
Show the answer
You can see through them
Its wings are clear, like windows!
Large parts of the wings are transparent and hardly reflect light.
Transparent regions with very low haze and reflectance, even at view angles up to 80 degrees.
-
What do glasswing caterpillars eat?
Which plants do glasswing caterpillars eat?
Which genus provides the larval host plants of G. oto?
- Grass
- Cestrum leaves
- Pine needles
Show the answer
Cestrum leaves
They eat the leaves of Cestrum plants.
The caterpillars eat Cestrum, shrubs in the nightshade family.
Cestrum (Solanaceae), including C. lanatum and C. standleyi in the wild.
-
What stops the glasswing's wings from shining?
What keeps the glasswing's clear wings from reflecting light?
What structures give G. oto wings their anti-reflective property?
- Tiny wax pillars
- A coat of mud
- Long feathers
Show the answer
Tiny wax pillars
Tiny pillars on the wings stop them from shining.
The wing is covered in tiny wax pillars of different sizes that cut down glare.
Irregular wax-based nanopillars with random heights and widths on the membrane surface.
-
Where do wild glasswings live?
Where do glasswing butterflies live in the wild?
What is the native range of G. oto?
- From Mexico to Panama
- In Antarctica
- Only in Germany
Show the answer
From Mexico to Panama
They live in Mexico and Central America.
They live from Mexico to Panama; ones in other countries live in butterfly houses.
Mexico to Panama (Haber); captive stock is exported widely from Costa Rica.
Places where you might see it
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Watch
Country
Costa Rica
Costa Rica is a small country in Central America between the Caribbean Sea and the Pacific Ocean. Volcanoes and mountains run down its middle, its forests are full of wildlife, and many national parks protect them. Since 1949 it has had no army. About 5.2 million people lived there in 2025.
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Watch
Country
Mexico
Mexico is a large country in southern North America, between the Pacific Ocean and the Gulf of Mexico. It has smoking volcanoes, ancient cities built by the Maya and other peoples, and about 132 million people, many of them in and around Mexico City.
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For parents & teachers
What children will learn
- Describe how the glasswing's wings differ from typical butterfly wings.
- Explain in simple terms how tiny structures can reduce reflection.
- Put the stages of butterfly metamorphosis in order.
- Discuss how studying animals can inspire new technology (biomimicry).
Recommended ages: 3 to 17 · About 15 minutes
Talk about it
- How might see-through wings help a butterfly? How could scientists test that idea?
- Why do you think engineers want glass that does not reflect light?
- Why might a butterfly house raise butterflies instead of catching them in the wild?
Try at home or in class
- Look at a window or a phone screen from straight on and from the side: notice how glare increases at steep angles, unlike a glasswing's wing.
- Place clear plastic wrap and colored paper over a picture and compare how much of the picture you can see through each.
Key vocabulary: transparent, scales, proboscis, metamorphosis, pupa, reflection
Where these facts come from
- Greta morgane oto (Hewitson, [1855]): type specimen and range , Butterflies of America
- GBIF Backbone Taxonomy and GBIF Occurrence Search , Global Biodiversity Information Facility (CC0 1.0 (backbone); occurrence counts are facts derived from records under CC0, CC BY and CC BY-NC)
- Wikidata , Wikimedia Foundation (CC0 1.0)
- Monteverde Butterflies: Greta oto , William A. Haber, Monteverde Butterflies (University of Massachusetts Boston)
- Behaviour and natural history of Greta oto in captivity (Hall, 1996) , Tropical Lepidoptera 7(2)
- The role of random nanostructures for the omnidirectional anti-reflection properties of the glasswing butterfly (Siddique et al., 2015) , Nature Communications (PubMed abstract)
- Developmental, cellular and biochemical basis of transparency in clearwing butterflies (Pomerantz et al., 2021) , Journal of Experimental Biology (PubMed abstract)
- Biomimetic omnidirectional antireflective glass via direct ultrafast laser nanostructuring (Papadopoulos et al., 2019) , Advanced Materials (PubMed abstract)
- Wikimedia Commons , Wikimedia Foundation (Per file: Public domain, CC0, CC BY or CC BY-SA only (credited on each page))
Checked, not yet human-reviewed. Last updated October 27, 2026. Spotted a mistake? Tell us.