y video was aimed at a Malay Lacewing nectaring on wildflowers along the old Gap road at Fraser’s when an unusual creature came swooping through my field of view. On looking up I found an odd butterfly with long tail, narrow black & green wings, decorated with clear, window-like areas. This fascinating creature was the Green Dragontail (Lamproptera meges) the smallest member of our Papillonidae family.

White Dragontail Lamproptera curious

Eight years later, on an early August morning last year my wife, Mireille called out from her painting across the New Road at Fraser’s “I think this is the one you’ve been looking for!” A distant photo was the best I could manage of a White Dragontail (Lamproptera curious) before he encountered a large spider web, broke free, & headed for the treetops.

Chapter 3 of the Dragontail epic played out at Doi Suthep National Park, Chiang Mai, Thailand, where Laurence Leong observed a specimen feeding like a hummingbird along the road. We timed the feeding periods to be of a minute or less repeated every 20 to 40 minutes around mid-day, but the erratic movement of the subject made photography nearly impossible. On review of our photos, we found 3 different subjects including both White & Green Dragontails. (The white specimen is shown here)

Oriental Clearwings
All of our moths & butterflies in Southeast Asia sport wing-coverings of tiny shingle-like scales. The word “Lepidoptera” is derived from the Greek, “lepido” meaning scale & “ptera” wings. Other families of flying insects such as flies, bees, wasps, & beetles have clear, scale-less wings. Some scales contain pigments to provide rich colors & patterns, while others contain microscopic ridges & bumps that cause interference in reflected light & produce a shimmering iridescence.

Species with transparent regions covering a part of the wings are called Clearwings. They are very rare in our region & the two Dragontails of our Papillonidae family are quite unique among our butterflies to be missing a part of their wing coloring. The clear areas on the wings result either from loss of pigment or loss of scales.

Hanmaiden moth Symtomoides imaon   Caeneressa diaphana

We in Southeast Asia have a better chance to see one of the Handmaiden moths that are day-flying members of the Arctiidae or Tiger moth family. Species such as Symtomoides imaon have clear wings & mimic the wasps. Should a predator not dislike wasps, the occasional bright body colors usually advertise a bad taste, so Handmaidens flourish.

The wings of many of our great Saturnid moths are decorated with ocelli or “eyespots” & some are clear as a small window. In the genus Attacus (Atlas) & Archeoattacus the clear windows are triangular & called “fenestras”. A powerful microscope usually shows a few clear scales near the center, surrounded by a scale-free circular or triangular region. For example, Archaeoattacus staudingeri, a rare cousin of Atlas, shows beautiful violet wings with clear triangular “fenestras”. *

Scaled Wings
Now my curiosity was aroused, so I searched for origins, & found that fossil evidence dates the first flying insect at about 400 million years ago. The dwarf plant kingdom was growing to 30 meters in height & the insects grew wings to keep pace with the flowers. Moths with scaled wings are thought to have evolved from the ancient caddisflies some 200 million years ago. Archeolepis, the oldest lepidopteran fossil dates from the Jurassic, & flew with the dinosaurs 190 million years ago. The early scales were flattened hairs, or setae, that produced coloration by interference of reflected light. There were no colored pigments then.

Bats were formidable moth predators, and during the Tertiary period, around 50 million years ago, some moths started flying during the day to avoid the bats. Their scales acquired a fine structure of nanometer-sized (one billionth of a meter) perforations to which granules of pigment could be added for more color. These were the early butterflies. Their eyesight became highly developed & color assumed great importance for species identification & mating. Our Striped Blue Crow, Malayan Eggfly, & the American Morpho are examples of butterflies with brown-pigmented scales that also show a beautiful blue iridescence when their scales reflect light.

We’re not sure why scales evolved in the first place but biophysicists are learning more about them every day. Recent studies show scales increase lift during flight by about 15% & improve aerodynamic maneuvering to escape their predators. Only ten years ago a patent was issued for a helicopter blade covered with butterfly-like scales for extra lift.

But scales hold more secrets. Engineers have spent years developing modern light-emitting diodes (LED) that use a photonic crystal to extract light from a semiconductor, mirrors to reflect the light, & micro holes to redirect the light outward. Pete Vukisic has found that a pigment in the wings of African Princeps nireus converts the ultraviolet from sunlight to a blue-green fluorescence; then it is channeled outward by mirrors & holes just as claimed in recent LED patents. He also found that the Banded Peacock scales use a multilayer structure with a blue annulus surrounding a yellow center to produce a green sheen (much as a color television), but the reflection of one of the colors is polarized! This appears to help the Peacock identify a mate. Now this nano-technology from nature is being applied to new bank notes & I.D. cards to defeat counterfeiters. Will our new currencies fly away faster when they add butterfly scales?

Neotropical Clearwings

Chorinea octauius

Alfred Russel Wallace coined the word “Neotropics” to signify “New World” or “American” tropics. The Neotropics tell a rather different story about clearwings. While birding the magnificent Atalaya trail on the eastern slope of the Peruvian Andes, down from Cusco, Mireille called “Isn’t this another one of your Dragontails?” It scurried down the road with darting flight at my approach & did resemble the Dragontails in both form & flight. But it displayed greater beauty with red & blue coloring on the hind wings & a black fringe on the clear fore wings. Chorinea octauius belonged to the Riodinidae or Metalmark family. Formerly grouped with the Lycaenidae (Hairstreaks), the Riodinids are found mainly in the Neotropics.

Ithomiidae
Continuing down the Atalaya trail, we encountered the Ithomiidae family, sometimes called “true” clearwings, endemic to the American tropics. You must believe in the Emperor’s New Clothes** to call these fellows “lepidoptera”. Some seem to have non-pigmented scales that scatter light, while others lack scales completely. Ithomiines are delicate insects with clear wings, long, slender bodies, & their lazy flight in the forest understory is reminiscent of our Wood Nymph.

Greta gardneri strikes an elegant pose while nectaring along the road, & displays crystal clear wings rimmed with golden brown. Hypoleria cajona is smaller with extended fore wing patch. Dircenna loreta shows lightly frosted wings & nectars from beneath the flower, while Thyridia hippodamia cetoides is attired in black for a more formal afternoon.
 

Greta gardneri Hypoleria cajona Dircenna loreta Thyridia hippodamia cetoides

Ithomiines usually are classed as a subfamily of the Nymphalidae, & are related to the Danidae. Around half of the species have exceptionally clear wings decorated with dark venation. They inhabit the dark forest under-story where they flit like ghosts & disappear into the shadows. (One species, Hypomenitis andromica, is called “The Ghost”). Some have white patches like Greta & Dircenna, while others show wings of yellow stained glass. Presumably Ithomiines of the under-story have shed their pigments & scales for a better camouflage since colorful Ithomiines inhabit the canopy & resemble Danids with orange, yellow, & black tiger stripes. Nearly all Ithomiines are distasteful to, & avoided by bird predators who identify them by color & flight pattern.

Tropical America also counts many clearwing species from other families including satyrines (the Rose Clearwing is considered to be the most beautiful) & lycaenids. All are partially transparent, like our Dragontails, and inhabit the forest under-story. Originally these species were thought to have lost their scales to mimic the distasteful ithomiines, but now it is believed that camouflage is the most important benefit & reason for clearwing evolution.

So if by chance one day you spot one of our clearwings & are captivated by its originality, try to make your way to the Neotropics where the above beauties await your visit.