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Think of butterflies and elegant creatures come to mind. Fritillaries with gaudy silver spangles, or kite-like swallowtails with their trailing wings. In the flashy, fancy world of butterflies, the great masses of dowdy “true blues” are so common that most people overlook them.

Eye in the Sky

But blues fascinate butterfly experts with their mind-boggling complexity. Novelist Vladimir Nabokov was obsessed with blues, and included references to them in his works.

More blue species are being discovered all the time, especially recently in South America’s high Andes. But because of habitat alteration, blues are disappearing at lower elevations almost as fast as new species are being found. Seven of the 18 endangered butterflies in the United States are blues.

A huge group of tiny, lookalike butterflies, blues are found on every continent but Antarctica. Some 1,400 species live in a variety of habitats ranging from beach dunes to high mountain slopes, typically in small colonies.


Known scientifically as Polyommatini, true blues are named for the flashy iridescent blue on the topsides of males—not truly blue but the effect of colorless, prism-shaped scales reflecting blue to our eyes. Poet Robert Frost described blues as “sky flakes.”

But the blue is a rare sight. Males sit watch on their territories most of the time with their wings up, exposing the drab surface beneath. Females don’t have reflecting scales. The black spots on the underwings of both sexes tend to make them look like gray construction-paper triangles sprinkled with pepper.

The excitement among blues experts these days is about finding new species, the equivalent of the Holy Grail in the world of biological sciences. The current hot spot is the high Andes of tropical South America, where until recently blues were thought to not be widespread.

“The region is rich in blues,” says Kurt Johnson, an authority on blues, formerly associated with the American Museum of Natural History in New York. “The interplay of latitude and altitude create temperate and alpine climates, sometimes within yards of one another.”

Seventy new South American blues have been discovered within the last decade, in part because of a reevaluation of pioneering research Nabokov did on a small collection blue specimens while writing fiction a half-century ago.

“We expect to find more in the great mountain ranges of China,” says Johnson, noting that until recently the region was closed to researchers.


As more new species are brought back, they are added to hundreds that have been sitting in museum drawers for decades, awaiting classification. The delay is a complicated issue, but it’s due mainly to the difficulty of distinguishing one blue from another.

“They don’t conform to our idea of species,” says Robert Robbins, an entomologist with the Smithsonian Institution’s National Museum of Natural History in Washington, D.C. Some blues that are considered the same species won’t mate, but some believed to be different species will. One blue is often so similar to another that they can be distinguished only by comparisons of microscopic anatomical parts. The debates keep things interesting for people who work among drawers of specimens.

But the real concern is how quickly blues are disappearing. Their characteristically small colonies, increasingly isolated by development, have made the group particularly vulnerable.

The Xerces blue, the first North American butterfly to become extinct through human interference, succumbed when its only known colonies in the sand dunes of San Francisco were wiped out by development. The Lotis blue also is considered extinct: a sweeping search of its northern coastal California habitat in 1993 turned up no signs of the species. The Karner blue, described and named by Nabokov, holds out in dwindling colonies in the Midwest and Northeast U.S., another victim of development. Oregon’s Fender’s blue was added to the endangered list just this year.

Worldwide, the list grows as well. The World Conservation Union (IUCN) has published a monograph on conserving the world’s blues, noting endangered species in England, France, Italy, Spain, Hungary, Russia, Greece, Yugoslavia, Bulgaria, Turkey, and Asia Minor.

“It’s the same in South America,” says Johnson. “Almost as fast as we’re finding them, we’re finding out they are in trouble.”

Eye in the Sky is a weekly series that brings you the story behind the headlines using satellite imagery, remote sensing, aerial photography, and maps. This feature is developed by National Geographic News with the sponsorship of the National Imagery and Mapping Agency (NIMA) and Earth-Info. Check out maps and imagery at

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•  The world’s many species of “true blue” butterflies escape notice because they are so small—most have wingspans of no more than an inch (2.5 centimeters). North America’s pygmy blue is barely the size of a shirt button.
•  In their caterpillar stage, blues lure ants with sweet-tasting secretions, called honeydew. The ants keep wasps and other predators at bay. Some female blues lay their eggs directly within ant nests for protection.
•  The caterpillars of blue butterflies typically require wild plants in the pea family, such as the lupine, a wildflower that moves in after wildfires. Changes in land use have made many of these plants scarce.

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People are often surprised to learn that Vladimir Nabokov, the literary genius who wrote Lolita, a novel about the seduction of a 12-year-old girl by a middle-aged professor, was also a self-trained butterfly expert.

Nabokov’s particular obsession was with “blues,” a huge group of small, drab butterflies with species all over the world. The writer’s precise mind was attracted to the fact that many blues are difficult to tell apart. The circumstances of Nabokov’s life turned him into one of the few world experts on blues.

Nabokov grew up the precocious child of an aristocratic family in pre-World War I Russia. Fleeing to Europe to escape the Bolsheviks and later to the U.S. to avoid the Nazis, Nabokov searched out blues wherever he was.

While writing fiction and teaching literature during the 1940s, he pored over trays of old museum specimens, reordering them according to contemporary theories. He described and named many North American blues, including the now-endangered Karner blue, and reclassified a group of 19 Latin American blues according to a system that was dismissed at the time, but is considered responsible in part for many species being discovered today.

Undoubtedly Nabokov could have had a golden career as an academic lepidopterist. His taxonomic studies, he told a reporter, were his favorite work.

“My work enraptures but utterly exhausts me,” he wrote his sister in 1945. “I have ruined my eyesight, and wear horn-rimmed glasses.”

More than once his wife Vera had to nudge him back to literature. Still Nabokov could not resist integrating his butterfly experiences into his many works of fiction. His short story The Aurelian is about a frustrated butterfly trader. His novel Ada, is about an entomologist. The series of motels in which Humbert Humbert ravishes Lolita was based on 150,000 miles of summer butterfly forays through the United States, Vera at the wheel.

Nabokov himself was unabashed in describing his passion for butterflies as “a momentary vacuum into which rushes all that I love.”