The Glass Winged Butterfly

Habitat:

The Glass winged Butterfly virtually found in all habitats in Costa Rica, including disturbed ones. It is often spotted passing through open areas, and sometimes visits gardens in the Meseta Central region.

Range:

This butterfly is found in Costa Rica on both the Atlantic and Pacific sides of the country, from 500 to 1,600 m. This glass wing ranges from Mexico to Panama.

Physical Description:

The glass wing is so named because of its gloriously transparent wings. A brown to reddish-brown border helps make Greta oto’s wings more visible. The upper part of the fore wing also has a white stripe through the brown region. Glass wings lack the tiny scales on most of their wings that give other butterflies and moths their colours, so the wings are, literally, see-through. It is very hard for the eye to follow as the butterfly dodges between under story plants among patches of light and shadow.

These are hard to spot even when the caterpillars are undergoing metamorphosis: they transform into small pupae with a chrome-silver colour that masks them as, perhaps, water glistening in droplets on stems. These pupae look like small mirrors.

Adults have scaly antennae and an elegantly thin, brown body powering the delicate, clear wings (the veins in their wings are visible). Males have an additional feature to their wings: on the hind wing is a small plume of fine hairs that stay tucked under the overlap of the fore wing most of the time. These become helpful in courtship.

Biology and Natural History:

Costa Rica is the home of 64 species of glass winged butterflies. This species, Greta oto, is one of the most abundant ones and is spotted more often than some of its relatives. It can be found all year long, but month to month a population may change Dramatically. An individual Greta oto may travel as far as 12 km in a single day while it is migrating.

As an adult, this butterfly drinks the nectar of certain flowers. The glass wing’s body absorbs chemicals from the nectar which make the glass wing taste unpleasant enough to discourage predators from eating it. The butterfly also uses the alkaloids to produce hormones.

To find a mate, males congregate in shady corners of a forest and give off these hormones 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.

Diet:

The host plants for Greta oto are two species of Cestrum. This glasswing (like others) also will feed on the droppings from birds that eat insects—by doing this, the glasswing gets amino acids into its diet.

Height:

The average length of a glasswing butterfly is 28 to 30 mm.