Like most of you, I spend my summer leisure time contemplating the tongue of the primrose moth.
OK, it’s not exactly a tongue. Butterflies and moths have a straw-like proboscis that they coil like a watch spring and unfurl to suck nectar from flowers. The primrose moth’s proboscis is about half the length of its body. That anatomy alone should be enough to generate interest in this insect. But now consider that the primrose moth is Pepto-Bismol pink with a lemony band at the tips of its wings. In that pink presentation and probing proboscis, the primrose moth offers us a lesson in form, function and evolution.
Primrose moths fly about searching for the evening primrose, a common garden and roadside plant with a dangling, elegant yellow flower. No one in Vermont or New Hampshire is far from an evening primrose blossom, which means no one is far from a primrose moth.
The primrose flower opens at night and then closes by day. So a visiting moth, if it sticks around until dawn, gets an intimate embrace of petals. Besides the hug, the moth gets nectar. I’m not actually sure what the plant gets out this deal. The moth doesn’t appear to pollinate evening primrose, according to botanists and scientific literature published on this particular encounter of insect and plant. In fact, the moth seems to get the best of this relationship. The females lay eggs on the evening primrose; when the caterpillars emerge they start munching the plant where it hurts – the flower buds.
In any event, most of the action happens at night, when the primrose springs opens its flower and the moth plunges headlong into the blossom. Even so, the alert flower watchers among us can witness, in broad daylight, this intimate meeting of moth and bloom.
I often encounter primrose moths still buried in a blossom the day after their night of binge-nectaring. They’re like a drunk passed out at the bar at dawn. Only the moth is harder to spot than a drunk. Those pink wings are buried out of sight in yellow flower petals. The only wing portions still visible are the trailing edges, the yellow edges, which conveniently resemble the yellow edges of the primrose petals. The moth has evolved with wise camouflage so it can sit and drink nectar, presumably unnoticed by predators.
One of my favorite naturalists, William Hamilton Gibson, once said we can hardly know the evening primrose until we know its nighttime visitor. Gibson was an exuberant 19th- century writer and illustrator. In his 1892 book, “Sharp Eyes,” a collection of essays and illustrations, Gibson revels in the moth and its blossom: “Is this a mere withered, useless blossom that droops upon its stem? Is it not rather the prettiest luminous fairy tent that ever sheltered a day-dream? Last night, when its four green sepals burst from their cone, and sprang backward to release their bright, glossy petals, a small moth quickly caught the signal, and settled in quivering contentment, sipping at its throat. Its wings were of the purest rose-pink, bordered with yellow.”
Gibson continues:
“In the color of its marking, we find an outward expression of its beautiful sympathy, the yellow margins of the wings which protrude from the flower being quite primrose-like, and the pink being reflected in the rosy hue which the wilting primrose petals so often assume, especially at the throat.”
Did you catch that? A wilted primrose flower turns pinkish. So a primrose moth merely sitting on the stem of the plant may resemble an old flower and still find safety in the color pink. (My photograph of two primrose moths on a flower, one inside and one out, is at: www.wingsphotography.com/primrose.html.)
What we cannot see in this little drama is the moth’s proboscis lapping nectar from the base of a primrose blossom. But we can imagine it. Take a close look at the flower. It has a long, slender tube with nectar, called the hypanthium, below the base of the petals. It’s a long reach for a moth seeking nectar. No matter. In nature form follows function. The moth unfurls its built-in drinking straw for a sweet reward, much as we depend on the drinking straw for that last half-inch of a milkshake.
So, this summer, get your favorite milkshake or maple cremee to go—and enjoy it in the good company of the primrose and its illustrious visitor.
Discussion *