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Leave the light on for them

It’s National Moth Week. Behold the nighttime visitors’ dazzling variety.

Just 16 of the hundreds of moths that alit upon the author's porch this week.Bryan Pfeiffer

Each night they fly to our front porches and backyards by the thousands. Some no bigger than a grain of rice, others the size of your palm, they twinkle gold and silver and glow hot pink, metallic blue, or 50 shades of brown. Our names for them attest to their diversity (and to the whimsy of biologists): chocolate prominent, beautiful wood-nymph, once-married underwing, tufted bird-dropping, blinded sphinx, and skunk twirler.

A tufted bird-dropping moth.Bryan Pfeiffer

These are among the moths now flying here in New England.

Let us dispense with moths’ general reputation as pests or drab creatures of the night. Ornate as any other insects, including butterflies, plenty of them fly by day. Yet what I find most compelling is that moths, more so than any other wildlife, bring to our doorsteps inklings of the profound diversity of life on earth.


Even among those of us who study it, biodiversity is somewhat of an abstraction. We’re still not sure how many living things inhabit the planet. A widely cited study puts the total at 8.7 million species, with somewhere around 1.2 million to 2 million of them described and named and known to science. So much remains vita incognita.

A garden tiger moth.Bryan Pfeiffer

How can any of us even sense such diversity? Birds get lots of attention. Even so, a dedicated birder in Massachusetts would need to be out and about much of the year to encounter even half of the state’s 500 or so recorded species. Plants aren’t as elusive. Yet a botanist might need a few years and many miles to see and identify more than 500 of the 3,500 or so vascular plant species in all of New England.

Moths put those numbers to shame. It isn’t only that they are more varied and abundant: My home state of Vermont, for example, has more than 2,200 moth species and only about 115 butterfly species. In the capital city of Montpelier, where I live, we have photographed more than 700 moth species at lights and on plants within city limits. Greater Boston hosts more than 1,000 moth species. Because moths, as caterpillars, eat plants, more plants means more moths, which is why small, leafy towns tend to have higher moth diversity than cities.


A luna moth.Bryan Pfeiffer

To be sure, other insects are more diverse than moths, and none more so than beetles. The English polymath J.B.S. Haldane, asked to speculate on the composition of the universe, is reported to have said that if the cosmos is divine in origin, the Creator “has an inordinate fondness for stars and beetles.”

Yet beetles do not visit us in multitudes, not like moths with their inordinate fondness for light. And during this National Moth Week scientists and other curious people around the world are beckoning moths by day and night — to enjoy and study them and to learn more about how we’re losing them, among other insects, in the extinction crisis. (Ultraviolet or mercury-vapor lights are best for studying moths, but porch lights also work, all of which we later turn off so that the moths can go about their usual nighttime business.)

The clymene moth resembles a flying Rorshach test.Bryan Pfeiffer

During two nights of blissful sleep deprivation in my small backyard last weekend, I photographed more than 120 moth species. Clymene moth is marked like a flying Rorschach test; Harris’s three-spot is inexplicably and undeniably pleasing; hologram moth does indeed cast an ethereal glow; and orange-headed epicallima is a fireworks show packed into a centimeter.


Even in our most unnatural of places, moths remind me of a world great and diverse and so undeserving of what we have made of it.

All we need is to leave a light on for them.

Bryan Pfeiffer is a semi-retired field biologist and lecturer at the University of Vermont. He lives in Montpelier.