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True Monarch of the Air

By “Awake!” correspondent in the British Isles

IN THE year 1919, aviators Alcock and Brown successfully made the first nonstop crossing of the Atlantic Ocean in a heavier-than-air machine. Understandably, the news flashed around the world. It was an extraordinary achievement.

Yet, strangely, 43 years earlier a feat of even greater wonder did not prove worthy of note, except in the records of a few entomologists. It was in 1876 that Danaus plexippus, commonly known in England as the milkweed butterfly, was reported as having been seen in the southwestern corner of the country. As the milkweeds, the only plants on which this butterfly can feed, are not indigenous to the British Isles, how had it arrived? The thought that it had flown from its American home, some 3,000 miles (4,800 kilometers) away, seemed absurd. Yet, in 1880 several specimens were captured aboard a steamer 200 to 300 miles (320 to 480 kilometers) into the Atlantic, outward bound from Glasgow. Speculation continued over a period of 70 years as some 150 specimens were recorded as having been seen or caught.

Since only two milkweed butterflies were found along the French coast, with just an additional four in Spain and Portugal, many persons reasoned that these creatures must have come east aboard ships, or that they even alighted on vessels en route. But to the present day their appearances have been frequent and many persons reason that maybe, after all, these fragile insects do make their own way on such an incredible journey. Why this view? Because of what is now known of the remarkable achievements of these creatures, identified in the United States and Canada as the monarch butterfly.

This handsome creature is immediately recognizable by its large orange-brown wings and strong dark-patterned veins. These markings have earned for it a third name, the black-veined brown. It is a common butterfly also familiar to the inhabitants of Australasia and the islands of the Pacific Ocean. Yet, its North American life-cycle is so intriguing that it has been the subject of a life-time study.

The Migratory Pattern

As a young lad, Dr. Fred A. Urquhart, a zoologist, first became interested in the monarch. In early January 1976, thanks in great measure to $24,000 (U.S.) received in research grants, Urquhart (now a professor at the University of Toronto) ended his search for the winter home of his elusive monarch after successfully tracing its routes of migration. Nearly 40 years of patient, painstaking research were at last rewarded.

Seeking to avoid the hard winter frosts, the monarch regularly leaves Canada and the northern part of the United States, flying in a southerly direction. Unlike birds, the monarch travels alone, each following its individual, instinctive path. Flying anywhere between five and 500 feet (1.5 and 152 meters) above ground, it meanders ever southward, traveling, at times, up to 80 miles (129 kilometers) a day. Many of these beautiful creatures perish during the journey, but a succession of broods, arising from the flight path, swell their numbers to a mighty throng.

As studies continued, more unexpected facts came to light. It was noticed that almost all male monarchs die on the return flight from their winter home. What, then, is the reproductive sequence? A close analysis has revealed that, with the declining daylight hours of late summer, the development of the female sexual organs of late-hatching monarchs is retarded​—and the same probably holds true of the males. As a result, infertile swarms of south-migrating butterflies grow to sexual maturity in their winter habitat as the days lengthen there. Breeding then takes place during the following northerly spring migration.

“A Glorious, Incredible Sight!”

In an effort to locate the winter resting place, various ideas were tried out. Initially, thousands of sticky labels were tenderly stuck to the butterflies’ wings. But a sudden night of heavy rain washed them off the sheltering monarchs. Eventual success came with special supermarket-type tags with their modern adhesive. Over the years some hundreds of thousands of the marked monarchs were released, and reports grew in volume as thousands of willing observers sent their findings to Toronto. The migratory pattern became clear, although the final destination remained a mystery, with the evidence pointing to Mexico.

The thrilling culmination of the search was reached when two volunteers, after crisscrossing Mexico for close to a year, stumbled onto the colony in 20 acres (8 hectares) of Mexican mountainside. Ten thousand feet (3,000 meters) above sea level, countless millions of monarch butterflies filled the air, covered the ground and festooned an estimated 1,000 oyamel trees. Capturing the thrill of his visit to this isolated location, Professor Urquhart, writing in the National Geographic magazine, thus described the wonders that met his eyes: “I gazed in amazement at the sight. Butterflies​—millions upon millions of monarch butterflies! They clung in tightly packed masses to every branch and trunk of the tall, gray-green oyamel trees. They swirled through the air like autumn leaves and carpeted the ground in their flaming myriads . . . I muttered aloud, ‘Unbelievable! What a glorious, incredible sight!’”

A Guiding Instinct

To see a single butterfly sipping nectar from a flower does much to enhance our appreciation of the Creator. But to see millions in one location to which they have flown for a distance of up to 3,000 miles (4,800 kilometers) logically prompts the question, Why? Even now, nobody can answer with complete certainty as far as the monarch is concerned. But it would seem that the cool winter temperature of Mexico’s Sierra Madre is just what is needed to help the butterflies to conserve their reserves of fat for their ensuing flight in the warming spring days.

Whatever the reason, man can but wonder at the faultless instinct guiding such migratory creatures. They weigh less than .009 ounce (250 milligrams) and yet have the ability to fly at 12 to 14 m.p.h. (19 to 23 k.p.h.). Moreover, the monarchs face storms and heat, open country, mountains and cities to find their way over thousands of miles to the foreign home they have never before visited, only to depart once more and never see it again.