The sheer size of the imperial moth isn’t the only thing that makes it unique.
An adult Imperial moth can have a wingspan up to seven inches, making it one of the largest moths in North America.
One morning late last summer, I opened my bedroom window blinds to discover what appeared to be a large autumn leaf Velcroed to the screen. A closer look revealed an alien of sorts, its buttery yellow-and-brown wings frozen in place no matter how much I studied it, not even when I measured its dimensions with a sewing ruler. The odd creature’s torso resembled a stubby cigar and its wings spanned more than five inches.
By nightfall, it was still there.
The mystery insect turned out to be an imperial moth, an uncommon but widespread species in the Blue Ridge states.
“They’re huge,” says Merrill Lynch, a retired Nature Conservancy biologist who consults on moth surveys and other projects from his home near Boone, North Carolina. (And yes, that’s his real name.) “They’re one of the largest, if not the largest, moths that we have in North Carolina or any southern Appalachian state.”
Although imperials can vary in hue—some sport more yellow, others more purplish-brown—“that pattern is pretty distinctive,” Lynch adds. “There’s no other moth that really has that color combination.”
An imperial moth caterpillar can grow to a length of about five inches.
The insect’s life cycle is, in some ways, just as intriguing. Hatched as a caterpillar with a voracious appetite, it feeds on the leaves of hardwood trees, particularly sweetgums, pines, oaks, maples and sassafras, until cooler fall temperatures send it underground, where it forms a cozy chrysalis. In spring and summer, the adult moths emerge.
By August or September, they’ve mated and lain eggs for the next batch of Imperials. “And then they die,” Lynch says. “It’s a very brief time when they’re actually flying around as adults.”
In fact, the majestic moths only live a week or two. Having eaten their fill as caterpillars and running on stored energy, they are born with no mouths.
Although the stunningly large caterpillars—they can grow up to five inches—are equipped with long hairs on their back, they’re harmless, Lynch points out. “Most of the spiky things are there to make them look like they’re venomous and not [safe] to touch.”
Moths, in general, he says, are sorely underappreciated. “Some people think of moths as these little brown things that fly into your windshield when you’re driving or that end up in your closet, eating your clothes. They definitely get a bad rap. But a lot of moths are just as beautiful, if not more so, than butterflies.”
They also outnumber their butterfly cousins. “The diversity is just mind-blowing,” Lynch notes. “In North Carolina alone, there are roughly 175 species of butterflies. There are at least 3,000 species of moths.”
How to Attract Imperial (and Other) Moths
You can increase the probability of seeing an imperial moth—or any other type, for that matter—by hanging a black light on your porch or from a branch in your yard. Attach a white cotton sheet to the wall or on a clothesline.
“The sheet reflects the ultraviolet light,” says Merrill Lynch, a retired biologist and moth enthusiast. “The moths can see it from farther away, and it gives them a place to perch. You can end up with hundreds of moths of all kinds of different species in one night that come to the light and rest on that white sheet.”
They’re also easy to photograph with a camera flash, Lynch notes. “The neat thing about moths is that you don’t have to go traveling around, looking for them. Wherever you live—you could be in the city, out in the country, anywhere—you can see lots of moths by just putting up a light and having them come to you. Keeping a list over about 10 years, I reported over 1,000 different species just in my yard.”
The story above first appeared in our September / October 2023 issue. For more like it subscribe today or log in with your active BRC+ Membership. Thank you for your support!