Almost Invisible: The Incredible Glasswing (Greta oto) Butterfly

Scienceray.com | 6 April 2010 | A butterfly with transparent wings? Surely not. Yet there is a species that exhibits this trait. Take a close look at the incredible Glasswing, an enchanting species that confounds science.

Greta oto may sound like the name of a silent movie star from Eastern Europe but is, in fact, the scientific name for one of the most exquisite – and little known – species of butterfly on the planet. This butterfly’s claim to fame is that its wings, spanning up to six centimeters, are almost completely transparent. That’s right, you can see just about right through them.

The common English name for this remarkable butterfly is glasswing, which in itself speaks volumes about the appearance of this small but unusual insect. However, it takes the romance languages to step in and give the butterfly the name which, for many, suits it best. The Spanish name for the glasswing is ‘espejitos’. Literally translated, this means ‘little mirrors’. Just a glance at the insect in question and one can imagine the thrill of pleasure when the moment of inspiration that came to its Hispanic name giver.

A close look at Greta oto reveals that between the veins of its wings the tissue is virtually see through (or, properly, translucent). Most other butterflies have colored scales which pattern the wings, quite often to ward off predators. The glasswing has another way of doing this entirely, but over the millennia it has evolved these specific wings to hide itself from predators rather than to warn them off. The only way that you can tell that it has wings at all are the borders, which are of a dark hue, sometimes bordering on the orange. Were it not for these borders, the glasswing would be more or less invisible to the human eye.

The glasswing is part of a specific clade of butterfly. Now for the science, as Jennifer Aniston might say. A clade is a ‘branch’ and is a term used in the taxonomy of species. When groups of species has a single common ancestor (which does not necessarily need to be extant) then it is known as monophyletic. The common ancestor of the glasswing is long extinct but the clade it belongs to is known as the clearwing clade.

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