Meet the cecropia moth, the largest moth in North America

June 23, 2017, 4:10 p.m.
cecropia moth
Photo: Cathy Keifer/Shutterstock

Butterflies get all the love. While the sight of a monarch or a painted lady can set human hearts aflutter, moths are often dismissed as a drab nocturnal nuisance, something that exists only to engulf porch lights and invade personal space.

It's worth looking past moth mythology, though, and seeing these strange insects with fresh eyes. They come in about 160,000 species worldwide, compared with roughly 20,000 species of butterflies. Most moths are nocturnal, and although many do have subtler coloring than their butterfly cousins, they're also far more diverse, vivid and captivating than stereotypes suggest.

In North America, one eye-catching example of moth glamour — and girth — is the cecropia moth (Hyalophora cecropia). With a wingspan up to 7 inches (18 cm), this burly lepidopteran is the continent's largest native moth. It naturally occurs in hardwood forests from the Rocky Mountains to the Atlantic coast, ranging as far north as Nova Scotia and as far south as Florida.

Pictured above is a male cecropia moth, which have larger antennae than females. Yet while that photo captures some of the cecropia's distinct coloring and charisma, this recent video from Instagram user hleexyooj offers a clearer sense of scale:

The video has also appeared in a popular Reddit post, where commenters both marveled and shuddered at the moth's size. "It's beautiful but if it landed on me I'd spaz out like an idiot," one wrote. Thankfully, cecropia moths — like most moths — don't really cause trouble for people, aside from crowding our electric lights in spring and early summer. Adults only live for a few weeks and are incapable of eating, since the sole purpose of their life stage is to mate and lay eggs. The caterpillars are also harmless, and despite feeding on leaves all summer, their naturally low abundance prevents significant damage to plants. According to the Florida Institute of Food and Agricultural Sciences, "this species is not considered a serious pest in any parts of its range."

Low population density can be a problem when looking for love, so male cecropia moths must rely on powerful senses to sniff out a female's pheromones — which he can detect from more than a mile away. Unfortunately for him, however, some bolas spiders can mimic the pheromones of a female cecropia moth, thus luring unsuspecting suitors into their clutches.

female cecropia moth laying eggs A female cecropia moth lays some of her eggs on a stalk of wildflowers. (Photo: Cathy Keifer/Shutterstock)

After the surviving moths partner up and mate, a female can lay more than 100 eggs, which she attaches in small groups to the leaves or stems of various host plants. Those eggs should hatch within one to two weeks, releasing larvae that then go through a series of life stages known as "instars," changing from black to yellow to green as they expand in size.

And if you thought adult cecropia moths were big, beautiful and bizarre, wait until you see their caterpillars:

Cecropia moth caterpillar Despite its prickly appearance, the cecropia caterpillar is harmless to humans. (Photo: Judy Gallagher/Flickr)

Finally, at the end of summer, the full-grown, roughly 5-inch-long caterpillar will seal itself in a cocoon. An adult cecropia moth will emerge the following spring, immediately plunging into the fast-paced world of adulthood. If you're lucky enough to see one, remember there's no need to flail or freak out. Just sit back and enjoy its beauty — and maybe turn off your porch light.

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