The little butterflies that look like mirrors; The Glasswing Butterfly (espejitos). 

Greta otois a species ofbrush-footed butterflyand member of the subfamilyDanainae, tribeIthomiini, and subtribeGodyridina, known as theglasswing butterflyfor its unique transparent wings that allow it to camouflage without extensive coloration.

The part of their wings that seem transparent actually have no coloured scales on them!

Isn’t it simply beautiful!

The glasswing butterfly is mainly found inCentraland northern regions ofSouth Americawith sightings as far north asTexasand as far south asChile. This butterfly thrives in thetropicalconditions of therainforestsin the Central and South American countries.

Distribution map of the glasswing butterfly.

While its wings appear delicate, the butterfly is able to carry up to 40 times its own weight- so they aren’t as delicate as they seem!

In addition to its unique and fascinating wing physiology, the butterfly is known for behaviors such as longmigrationsandlekking.

The glasswing butterfly ismigratoryand travels up to 12 miles (19km) per day at speeds of up to 8 miles per hour (13km/h). It migrates in order to changeelevations, and this migration causes there to be population density differences in varying geographical areas.

The glasswing butterfly is is one of the most abundant butterflies in its region and is spotted more often than some of its relatives in Central America. It can be found all year long, but month to month a population can fluctuate.

They lay their eggs typically laid on plants of the genusCestrum, a member of the nightshade family of plants, which serves as a food source for later life stages.

Below are some examples of plants from the genus Cestrum.

Yellow cestrum- cestrum auratiacum.
Cestrum fasciculatum.
Night-blooming jasmine- Cestrum nocturnum.

Thecaterpillarsof the glasswing butterfly have green bodies with bright purple and red stripes. The larvae are cylindrical in shape withdorsal projections that are smooth with filaments. These properties make the larvae extremely reflective, which essentially causes them to be invisible to predators.

Thepupaeare silver in colour and during the fifthinstar stage (see butterfly reproductive cycle below), the pupa produces asilkpad on the lower surface of leaves through four spinning movements, onto which it attaches.

The silk fibers are important in providing greater flexibility to the pupa attachment. The cremaster, a hooked bristle-like structure on the pupa, attaches to this silk pad by a series of lateral movements of the pupasposterior abdomen.

The silk pads are essential for the pupas, attachment failure occurs when the silk pad breaks.

Researchers have found that the pupa attachment to have high tensile strength and toughness, which actually prevents the pupa from being pulled bypredatorsor breaking off in the wind, allowing them to safely swing and move whilst attached safely to the host plant.

Lantana flower nectar is a food source for adult glasswing butterflies.

Birdsare the most common predators of this butterfly. The glasswing combats predators by consumingtoxinsthrough plants of genusCestrumand familyAsteraceaein both the caterpillar and butterfly stages. Toxin consumption gives the butterfly a foul taste that discourages predation. It also utilizes its transparency to hide from predators bycamouflaginginto the background during flight. Transparency is a rare trait amongLepidoptera, since they more commonly usemimicryto ward off predators

Also…

To find a mate, males congregate in shady corners of a forest and give off these pheromones to call females. The long hairs that males have tucked away help magnify how stinky they are, sort of the way hair makes an armpit smell stronger. Females smell the males and join the congregation to find a mate.

In order to attract females, male butterflies formleks, or large gatherings where males compete for mates. They gather in shaded areas of therainforestand competitively display themselves in order to attract mates. Male glasswing butterflies release pheromones during lekking in order to attract females.

The pheromones produced are derived frompyrrolizidine alkaloidsthat the butterflies obtain through their diet of plants of the familyAsteraceae. The alkaloids are then converted to pheromones through the formation of a pyrrole ring, followed by ester cleavage and oxidation.

pyrrolizidine alkaloids

The following national parks ofCosta Ricacurrently feature the glasswing butterfly and are working on their conservation:

Guanacaste National Park,

Rinc籀n de la Vieja National Park,

Monteverde Cloud Forest Reserve,

Palo Verde National Park,

Carara National Park,

Po獺s Volcano National Park,

La Selva Reserve and Biological Station,

Juan Castro Blanco National Park,

Iraz繳 Volcano National Park,

Chirrip籀 National Park, and

La Amistad International Park.

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