It’s not news to anyone that many animals, if not most, possess a far more sophisticated sense of smell than we. For us English-speakers, even the word “smell” conjures malodorous scents before it reminds us of fresh-baked bread. “You smell,” for example, is never a nice thing to hear, unless it’s qualified with “…nice,” or “…like fresh-baked bread.” Though it is the sense most associated with memory, and the larger part of our ability to taste, we tend to ignore our day-to-day scents and only appreciate them when they are new, or particularly wonderful or evil. A dog, for example, seems much less judgmental about the smells in its world, being equally appreciative of flower gardens and strangers’ butts.
But most animals, despite their superior noses, are simply highly attuned to one or a few scents. Bears have the greatest senses of smell, about seven times greater than a bloodhound’s and over 2,000 times better than a human’s, and can smell a carcass from 20 miles away, if the wind is right. But bears are generalists, so they are attuned to a wide range of things. A specialist, like a turkey vulture — the best nose in the bird world, though most birds have little to no sense of smell — can detect rotting meat from several miles away and several miles in the air, but only rotting meat. A shark can detect a single drop of blood in the water from half a mile away. A salmon can smell the particular melange of moss, roots, and soil of its native stream in the ocean at a ratio of one part per trillion. But when it comes to the scent of a woman, there is no bloodhound like a Saturniid moth.
The Saturniidae are a family better known as wild silk moths, for their silky cocoons. But their fame among lepidopterists is won for their enormous size and their breathtaking beauty. These are the largest of the moths and butterflies, making them some of the largest insects in the modern world. The Saturniids include the world’s largest moth, the Atlas Moth of South America:
And the largest moth in North America, the Cecropia:
The most beautiful moth, in my opinion, the ethereal Luna Moth:
And the star of our show, the Polyphemus:
Named for Polyphemus, the giant cyclops in the Odyssey (though I keep counting two false eyespots, no matter how I squint), this king of the night wears an equally impressive crown of antennae, far larger than his queen’s. As a caterpillar, he was voracious, but now that he is an adult, he lacks both mouthparts and a digestive tract. So the feathery antennae are not to find food, but a mate. She will be resting against a tree somewhere, producing a perfume of pheromones from her abdomen, each long-stranded molecule swirling in the tiny eddies of wind created by the leaves and branches. It is siren song to a male Polyphemus. The 60,000 sensilla — the sensory hairs — on each antenna bear 150,000 receptor cells, all programmed both to recognize individual parts of a pheromone molecule and to send impulse signals to the part of his brain that controls behavior. Upon touching any part of a single molecule of her scent, the moth is irresistibly drawn to her, body and soul. He is no longer in control of himself, but commanded by a single silent word sent to him over a long dark distance, a whisper on the wind.
In fact, if you whisper the word “love,” that one exhaled syllable is a wilderness of scents to a moth. One note of air in the symphony of the night forest is excruciatingly loud: it might contain particles of pine and oak pollen, the bouquet of mildew and skunk and wild rose, fruiting mushrooms and dirty water and bobcat scat and the stink of every other desperate, lovelorn insect tonight. But the Polyphemus moth isn’t listening for these, only the chemical voice of his future beloved. He is so attuned to her come-hither scent that he can detect a single molecule of her in a cubic yard of air, picking it out of trillions of molecules like a diamond earring from the sand. He can smell her from seven miles away. If it is raining, he will fly through the rain to her. If the storm blows against him, if there are cliffs to climb, he will still sail the merciless night to find her.
He does not fly directly into the wind, instead using a fairly sophisticated technique called anemotaxis: by measuring wind speed and direction against his own movements and the increasing potency of her, he can effect a beeline for her even if she’s not directly upwind. The two antennae work like a witching rod or a snake’s tongue, and the moth zig-zags the way a bloodhound sways its head from side to side, nose buried in the criminal’s tracks. When we walk, the grass catches part of us, and so the female moth leaves her pheromone fingerprints on leaves and the surface of water, clues and hints for the male to trace. She is not here, but she touches the treetops and stoops to the closed trilliums. She is not here, but he can hear her ghost singing in the forest. Drop by drop, molecule by molecule, he struggles towards her, crashing through the undergrowth, drumming his enormous wings against the beech leaves. The great yellow owl eyes on his wings flicker, searching. There are real owls here, hungry owls listening for him in the night like stethoscopes listening for the beating of a poisoned heart. But he cannot stop. He has heard her name, found just an iota of this moth he has not met yet, and he is no longer his own. He is hers, and he will collect the drops of her one by one as he swims to her, thrashing like a killer’s mind, a beautiful delirium, the drowning man’s breaststroke. It is not his journey; it is her command. It is not his mystery to solve, but her seeking him. She beckons, as if with a crooked finger, across the treacherous river of night. He leans in over the miles, a living kiss without a mouth.