The Magical Glass Wing Butterfly

Elegance and Illusion come together in this wonder of nature – a butterfly with translucent wings designed to help it camouflage into its surroundings, not unlike the glass frogs who share this amazing feature. The Glass Wing is also known as Greta Oto or Espejitos, a Spanish word meaning ‘Little Mirrors’, a fitting nickname for these amazing critters.

Have you seen the Greta Oto? A true marvel of nature! c/o Scott Wylie, wikicomons.

This is a small butterfly – with a wingspan of 6cm and length of 3cm and under 1 gram in weight. Tthe Glass Wing is nevertheless very tough, strong, and well travelled – we talk about all of that below.

Table of Contents

DOUBLE DEFENSE – TRANSLUCENCY AND TOXICITY

The butterfly’s translucent wings help it blend into its surroundings while resting or flying. The wing edges show color, but most of the surface stays clear. This rare trait makes the butterfly hard to spot. Birds, the main predators, don’t often encounter translucent wings. They look for bold patterns and colors. This unfamiliar camouflage throws them off and gives the butterfly a better chance to escape.

The translucent wings with edge coloring act to make the butterfly less visible to predators. c/o Eddy Van 3000, wikicommons.

And if the translucency wasn’t enough, the caterpillars and butterflies have evolved a taste for Cestrum plants, a nightshade. They also love to feast on certain species of Asteraceae, which is a flowering plants that includes daisies and sunflowers. These two types of plants contain certain chemicals, present in the nectar, which are harmless to the Glass Wing but very unpalatable and even toxic to many predators which would otherwise feast on them. Fittingly, the Glass Wing likes to lay its eggs on these plants. This ensures the caterpillars start their days with this life-saving trick up their sleeves. The induced toxicity & unpalatability is a primitive form of chemical warfare that is also used by the famous Blue Morpho butterfly.

A Cestrum plant native to Costa Rica - every part of this plant is poisonous to humans, yet it is food to the Glass Wing caterpillars. c/o Mbdortmund , wikicommons. — A Cestrum plant native to Costa Rica – every part of this plant is poisonous to humans, yet it is food to the Glass Wing caterpillars. c/o Mbdortmund , wikicommons.

NANOTUBE WINGS

Greta Oto’s wing translucency is very efficient, with only about 2% of the light hitting its wings being reflected. The wings look see-through for three main reasons:

They don’t absorb much light, so most of it passes through.
They don’t scatter light, which keeps the wings clear instead of cloudy.
They don’t reflect much light, even when light hits from different angles or colors.

The Glass Wing's translucent wings are a true work of natural engineering! c/o Brn Assis, wikicommons. — The Glass Wing’s translucent wings are a true work of natural engineering! c/o Brn Assis, wikicommons.

✨ The secret lies in tiny structures called nanopillars on the wing surface. These are:

Super small—smaller than the wavelength of visible light.
Tall and thin, with random heights and widths.
Arranged in a way that creates a smooth transition between air and wing material, reducing reflection across all colors and angles.

A photograph of the nanopillars. The scale is shown in the lower right section - the 1µm (micrometer) unit is 1/1000th of a millimeter. So to cover the length of 1 millimeter, about 400 of the photos above would need to be laid out side-by-side. c/o Radwanul, wikicommons. — A photograph of the nanopillars. The scale is shown in the lower right section – the 1µm (micrometer) unit is 1/1000th of a millimeter. So to cover the length of 1 millimeter, about 400 of the photos above would need to be laid out side-by-side. c/o Radwanul, wikicommons.

The nanopillars also sit on tiny pedestals, which make the anti-reflective effect even stronger. Plus, the wing surface has fine hair-like features (called microtrichia) that keep it smooth and help repel water.

Some serious engineering has gone into making those translucent wings work! c/o David Tiller, wikicommons.

A HEAVY LIFTER!

The Greta Oto looks fragile and ethereal, but it carries up to 40 times its own weight. That’s like a man lifting a full-sized SUV as easily as a grocery bag. Or a woman hoisting a rhinoceros or delivery van overhead without effort. This butterfly’s strength defies its delicate appearance and showcases one of nature’s most surprising feats.

Researchers believe two main factors explain this butterfly’s strength. First, Greta Oto lives a fast-paced life. It can migrate up to 20 km per day, flying at speeds of 13 km/h. That demands serious endurance.

Second, males engage in lekking—a competitive mating behavior. They perform aerial displays and acrobatics to attract females. This courtship requires power, stamina, and precision in flight. More details on migration and lekking appear below.

MIGRATORY BUTTERFLY

The Glasswing butterfly travels far—up to 20 km in a single day. It migrates for two main reasons. First, it changes elevation to find better food sources. Second, it moves with the seasons, shifting from wet to dry areas to seek more suitable climates.

This behavior helps the butterfly expand its range. By following weather patterns and blooming cycles, it thrives across diverse habitats and stays in sync with nature’s rhythms.

A truly mobile butterfly, the Greta Oto moves up and down the mountains in search of food and better weather. c/o gailhampshire, wikicommons.

LEKKING

Lekking is a mating strategy where males gather in a shared display area, each defending a small territory – usually in groups of up t0 20 butterflies. The Glass Wings don’t fight physically, but they compete by showcasing their fitness through pheromone release and territory quality. Females visit these leks and choose mates based on the males’ performance and chemical allure.

These lekking spots are often near host plants or nectar sources, especially those rich in pyrrolizidine alkaloids (like Aster flowers), which males use to produce potent pheromones. By gathering in groups, they amplify the chemical signal, making it easier for females to locate them.

Though not as flamboyant as bird dances, males may engage in subtle wing posturing, aerial movements, and scent release to assert dominance and attract mates.

FEEDING THE GRETA OTO

Greta Otos love backyard feeders – and are not very discriminating when it comes to the food on offer. Over-ripe and rotting fruit are the favorites of Glass Wings – scraps of mangoes, bananas, or pineapples can be left on dishes or raised platform. These will attract different butterfly species and, with luck, the Glass Wing will be amongst them.

Greta Ota munching on a banana. c/o Tim Sheerman-Chase, wikicommons.

Although widely practices, avoid feeding the butterflies with sugar water – because it lacks amino acids, minerals, and alkaloids found in real nectar. Fruit are a natural part of their diet, but still you should not put them out every day unless you live in an area where wild flowers and fruit are sparse, like a city. You don’t want to take the butterflies away from a very important task – pollinating local flowers.

Offering sugar water to the Greta Oto should be avoided - this provides empty calories and is deficient in important nutrients the butterflies need for proper functioning and development. c/o Judy Gallagher, wikicommons. — Offering sugar water to the Greta Oto should be avoided – this provides empty calories and is deficient in important nutrients the butterflies need for proper functioning and development. c/o Judy Gallagher, wikicommons.

THERE’S NOT MUCH INFO!

Spotting a Greta Oto is a rare treat. This delicate creature remains little-known and lightly studied. It’s not endangered, and it doesn’t flash bright colors—but it still captivates.

Greta Oto has quietly slipped through the cracks of research. Yet it thrives in Costa Rica’s tropical landscapes, adding subtle beauty to the country’s rich biodiversity. Its quiet presence makes it one of the region’s most enchanting natural wonders.

The Greta Oto is not very well researched and documented - so these amazing creatures still remain a bit of a mystery although they are quite common across their range. c/o Tim Strater, wikicommons. — The Greta Oto is not very well researched and documented – so these amazing creatures still remain a bit of a mystery although they are quite common across their range. c/o Tim Strater, wikicommons.

Imagine living in a paradise where surreal creatures like the Greta Oto are a part of your everyday experience! And when the see0thru butterflies are being too shy to come out of the jungles , the monkeys, macaws, sloths, coatis, toucans, poison dart frogs and many other amazing jungle creatures will fill in the gap! RE/MAX WE SELL PARADISE is your trusted real estate partner – while you browse the hundreds of properties available in our area, we are waiting for your call!

Cover photo c/o NH53