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Two summers ago, a giant subtropical moth flew north hundreds of miles to my aunt’s garden in Wisconsin, where it stopped to rest on the fence above the garden hose. It was dark brown with eyespots, spangles, and a purplish, gleaming band across its wings: a female black witch moth, Ascalapha odorata.
Black witch moths are rare finds in Wisconsin, but their unusual migratory behavior is well-documented. Each summer, a few of these moths leave their species’ year-round home in Central America and the Caribbean to fly north on currents of warm night air. Some reach Canada by June.
The witches are very strong fliers: One was observed recently on Quebec’s Magdalen Islands in the Gulf of St. Lawrence, more than 50 miles from the nearest land and 1,600 miles north of the Tropic of Cancer. The moth is familiar to people in Mexico, where it’s called the “mariposa de la muerte,” and Jamaica, where it’s called the “duppy bat”: the embodiment of a restless soul.
It’s amazing that the same species which is known for flying into people’s houses in the Caribbean also visits Maine cottages and spruce forests. But, like the leopard in “The Snows of Kilimanjaro,”1 it remains unclear what exactly the dispersing moths are seeking at such high latitudes, where potential mates are few and far between.
Sometimes, they appear to be propelled by the remnants of tropical storms, but it’s possible that they’re merely adventurous, or in search of something that we can’t comprehend. Often, the moths that travel farthest appear haggard, with worn-out wings, suggesting an almost manic desire to move as far and fast as possible.
In midsummer, as the northern hemisphere tilts toward the sun and heat drifts up across the continent, the black witch is not the only creature to become untethered. Wading birds like herons, limpkins, and gallinules—confined to Florida and Texas for most of the year—also float north to unexpected places. Last summer, a swath of states including Michigan and New Hampshire were visited by roseate spoonbills, which normally live no farther north than the Gulf Coast.
The black rail, one of America’s most secretive birds, also blinks in and out of inland marshes at this time. Like a firefly or a satellite, it signals only occasionally at night, and moves between detections. Because of its rarity and inconsistency, the rail’s freshwater range in the Midwest—separated by hundreds of miles from its strongholds on the coast—is depicted as little more than a dotted line and a question mark. As in the case of the moth, the phenomena that motivate rails’ movements are not well understood.
Humans, too, have set their sights higher than ever in July. In 1969, the first moon landing occurred on July 16, and earlier this month, NASA released the first images of the universe taken by the James Webb Space Telescope. We cannot help but look up, it seems, on summer nights. Like moths and rails, we seem to harbor an innate desire to explore the unknown darkness.
John Steinbeck, writing in The Log from the Sea of Cortez, proposed some intriguing, if unscientific, theories about the moon and its impact on the human psyche (though Steinbeck did not mention it, the word “lunatic” actually refers to people driven crazy by the moon’s phases).
Noting that humans briefly develop vestigial gill slits while in the womb—which are evidence of our evolutionary past—Steinbeck proposed that we might also harbor memories associated with certain environmental stimuli, the most salient one being the memory of the moon’s gravity, which has an impact on tides and currents, and thus the life cycles of many aquatic animals.
“Perhaps, next to that of the sea, the strongest memory in us is that of the moon,” he wrote. “Now if we admit for the moment the potency of [its] tidal effect, we have only to add the concept of inherited psychic pattern we call ‘instinct’ to get an inkling of the force of the lunar rhythm so deeply rooted in marine animals and even in higher animals and in man.”2
Though I like the idea of terrestrial animals sensing the gravitational pull of the moon, it seems to me that the moon’s light is likely to have impacted our evolution even more during the millions of years that we have lived on land.
Moonlight and firelight were the only significant sources of light at night for millennia, and humans are highly attuned to them. In total darkness, we can perceive the light of a single candle more than a mile away: a very useful thing, if one is looking for home, or scouting the campsite of strangers.
Both moths and nocturnally migrating birds are drawn to human signal lights in darkness. Millions, in fact, die nightly as they hurtle themselves into glass, seemingly lunatic with desire to touch the orbs glowing behind invisible walls.
In reality, for both moths and birds, the collisions may have more to do with a scrambling of navigational systems that evolved by moonlight and starlight than a siren song emanating from skylines. We should think of these winged creatures first as pilots: They know where they are going, and are merely confronted with unfamiliar obstacles en route. Death is collateral.
When human pilots first broke through the veil shrouding the earth and reached the moon on a hot July evening fifty years ago, they were able to do so because their navigational systems were calibrated very carefully. Their mission was both a feat of ingenuity and the consummation of a dream.
We have also come to think of it as an example of human exceptionalism, for the Apollo astronauts, of course, reported no other life on the moon. Still, I have wondered whether—if they had spent more time traversing its surface—they would not eventually have come upon the body of a migratory bird or moth: broken slightly by the impact, but otherwise perfectly preserved. ◆
“Close to the western summit [of Kilimanjaro] there is the dried and frozen carcass of a leopard. No one has explained what the leopard was seeking at that altitude.” —Ernest Hemingway, “The Snows of Kilimanjaro” in The Complete Short Stories of Ernest Hemingway (New York: Simon and Schuster, 1987)
Steinbeck, John and Edward Ricketts. The Log From the Sea of Cortez, Ch. 4. (New York: The Viking Press, 1951)