Luna Moths: The Elegant Pie Fairies of North America

A luna moth is basically the combination of a fairy, silk, and a slice of key lime pie – in other words, the perfect arthropod. Despite being native to the eastern United States and Canada, however, I have never come across one of these beautiful insects in the wild. Or ever, really. They’re one of my favorite Lepidopterans, yet no matter how hard I’ve looked I’ve still never been able to find one.

All right everyone, looks like I’ll be taking a break from blogging to go live in the woods until I find a luna moth. Ta-ta.

…Although I guess I ought to at least finish this post first. Then it’s off to the wilderness to track down pie fairies.

Despite “luna” being in the name (luna is the Spanish word for moon), these elegant arthropods begin their time as moths at daybreak. The luna moth caterpillars eat and grow for about a month before spinning their cocoons, which they will metamorphose inside for another two to three weeks. They emerge as beautiful moths in the early morning rather than under the moonlight, but their wings won’t typically be fully developed for flight until nightfall. The “luna” in luna moth actually refers to the yellow circles on their wings, which resemble crescent moons.

Another strange-but-true factoid about these elegant pie fairies – they don’t eat pie. Or anything, for that matter. Along with fireflies and a variety of other insects in their final stage of metamorphosis, luna moths only eat in their larval form. As moths, they don’t even have mouths. Being unable to eat means they only live as moths for about a week, but that gives them just enough time to mate and lay eggs. I guess now we know why caterpillars are so hungry – they’ve gotta use their taste buds while they have ‘em.

That’s right, insects can taste. They don’t have taste buds on their tongues the same way we do, as they don’t exactly have tongues, but they can taste with their other mouthparts and that works just as well. The best part is, they tend to like the sweet stuff: someone get these luna moth caterpillars some pie!

In all honesty, these caterpillars would benefit a lot more from some good tree leaves than a slice of a pie, so we’ll just cut the leaves into little triangles and tell them it’s pie.

Just because luna moths can’t eat in their adult form doesn’t mean they can’t be eaten themselves, as they often fall prey to larger insects, bats, and even the occasional owl. Fortunately, our beloved pie fairies have a few tricks up their sleeves to ward off foes.

We all know how bats use echolocation to track down insect prey, but they’re not the only ones who utilize sound as a weapon. Luna moth caterpillars will stand upright and click angrily at their foes to ward them off. I don’t know about you, but if a big larva reared up like a horse and started yelling at me I’d probably back off. Just in case they run into any particularly brave adversaries, however, these caterpillars make good on their clicking threat and throw up. That sounds like an odd defense mechanism to say the least, but would you want to eat something covered in barf? Neither would many caterpillar predators.

Luna moth adults have a good strategy for avoiding being eaten as well. Remember the bats? Unfortunately for them, echolocation has its weaknesses, and luna moths can disrupt the soundwaves these flying, fuzzy mammals with the tails on their wings. I wonder how that works though; can they change the picture that gets sent back to the bats and trick them into thinking their swooping down on an owl or a goose or a flying bear instead? Come on, entomologists, I need answers.

If you’re like me and you want to go scouring the woods for a luna moth now, head to your nearest deciduous forest at night. With friends. Don’t wander into the forest alone, kids, that’s not safe. You may be able to spot luna moths among the trees that their young will feed on as they look for a place to lay their eggs, such as sweetgum, hickory, and oak trees.

While luna moths’ conservation status is currently listed as “secure,” they can still be pretty tricky to find thanks to their nocturnal habits and short adult lifespan. The best odds of finding one of these moths is in May or June – which means it looks like I’m postponing my camping trip until next year. Oh, well. It’s getting colder out anyway, a summer moth safari may be more pleasant.

As I learn more about arthropods working on this blog, I sometimes find new information that I would have put in past blogs if I had found out about it earlier – for example, I’m kicking myself for not mentioning that some fireflies are mouthless in the firefly blog. While I’m going to try to limit each arthropod to one post, I may have to return to luna moths again if I ever actually come across one so I can tell y’all what they’re like in person.

I mean, it’d be a crime if I ever ate key lime pie in the woods surrounded by pie fairies and didn’t tell anyone about it.