Moonlight Becomes You

Luna Moth by Heather HinamSome childhood memories just seem to stick with you, lodging in your grey matter and coming back to haunt you at random intervals.

One that has been showing up quite frequently on the mental playlist lately harkens all the way back to a stint at Girl Guide Camp at Bird’s Hill Park, just northeast of Winnipeg over 20 years ago. It was a dark and muggy mid-June night as we trucked off as a group of giggling girls to the public washrooms. In the orange haze of the sodium lights, we heard a shriek of fright and immediately thought a bear had found its way into the campsite. Nervous, we crept around the corner toward the source of the sound and found girls from another troupe cowering under the lights over the door, pointing to the wall.

The source of their terror? Luna moths.

Looking back, I can see how these fluttering, green giants could scare the bejeepers out of a bunch of city girls. However, I was more fascinated than frightened by these enormous moths; still am.

I went a couple decades without seeing them again until one June day a few years ago. A friend came into work at the resort on Hecla Island and announced that they had a giant green moth on their door screen. Needless to say, I was over there with the camera in short order. The image above was the result.

There’s just something compelling about these ghostly green insects that float, like the moonbeams their named for, through the early summer nights.  With a wingspan of about 4 inches, they’re one of the largest moths in Canada and arguably one of the most beautiful; but few people get the chance to see them. They’re nocturnal and only exist in their adult form for about a week, so to catch a glimpse of these beauties, timing is truly everything.

They actually have a lot in common with a much more abundant and much less revered insect that emerges a few weeks later here in the north woods, namely the fishfly. Like its very distant cousin, adult luna moths have one purpose: to mate and deposit eggs to ensure the next generation. Like fishflies, these Saturnid moths have no mouths and do not feed. Their large, fuzzy bodies and consequently larger energy reserves from their larval stage allow them to live longer than the fragile fishfly.

In the dark labyrinth of the nighttime forest, finding a suitable mate is hard work, so male lunas can travel kilometres, tasting the air with their antennae for the pheromones drifting from a ‘wick’ extending from the abdomen of a waiting female.  Because they’re needed for this function, the antennae of male luna moths are much larger and fluffier than those of females, making the sexes fairly easy to tell apart. The moth pictured above is a female. Once the sexes find each other, they lock together in copulation for up to 20 hours before she sets off to lay her eggs. A female can produce up to 300 eggs, scattering them around the forest, a half dozen or so at a time, on the underside of birch leaves to incubate for almost two weeks.

The larvae are just as impressive as the adults, a bright, almost fluorescent green caterpillar that you can find trundling along the trunks and branches of its host plant, munching away on the leaves and growing up to 4 inches long by the time it sheds its exoskeleton for the fifth time (a process known as ecdysis).

Up here in Manitoba, where the summers are not long enough to allow for two generations, lunas overwinter as pupae in their cocoons. It isn’t until the following June that they will emerge from this stasis, all crumpled and fragile. Slowly, over at least half an hour, the new moth will pump hemolymph (insect blood) into their wings, ‘blowing them up’ until they harden into their characteristic green sails. It’s an event you can witness first-hand if you’re lucky enough to find a caterpillar before it pupates and keep it at home over winter. I’m actually planning to try and do just that later this summer so that I won’t miss the emergence of one of my favourite denizens of the dark.

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10 thoughts on “Moonlight Becomes You

  1. Wow! Thank you for this blog!
    My first encounter with a Lunar Moth was in upstate New York, there it was the huge pale green creature attached to the door of a building we called the “temple” ! I had my camera, it never moved…
    Than in NJ a few years later, I found pieces which I collected and brought home, I am like a kid that way. Than once later, while exploring an old lake, that once was a public lake, I was graced with another sighting.

    I don’t think I ever looked up the details, so I am grateful for your nature science lesson!

    • Thanks for stopping by, Jeff. I’m very glad you enjoyed it. I can completely relate to your collecting of interesting tidbits of nature. I have everything from butterfly wings to a chinchilla skull stashed away for interest and education purposes.

      I’m glad my blog enhanced your already great encounter with this remarkable insect.

  2. Thanks Heather, I have always loved the Luna moth. I remember them knocking against our cabin window in Grindstone late at night when I was a little girl, they were always so beautiful and fascinating!! We currently have one in a shadow box in our living room as we found the bright green caterpillar a few years ago up in Hecla. We placed it in a container and it cocooned and wintered in our garage and one early spring morning we found our glorious luna out of her cocoon sitting on a branch. We have her preserved and I have a little piece of Hecla/Grindstone in my living room each and every day!

    • Hey Catherine! I remember you guys capturing a luna caterpillar. I’m glad to hear it went through metamorphosis successfully. That must have been an awesome experience. If you’re ever looking to revisit Grindstone, you’re always welcome at my place 🙂 We’ll miss you guys.

    • Thanks, Sybil. I really is all about timing. They seem to come out in the first few weeks of June here, depending on the weather. There may be some reports for Nova Scotia somewhere that might help you narrow down a window. Maybe next year.

  3. You know I love this image. Your presentation is so artistic as always and I love the moth’s colour and the way it’s hind wings create a kind of gangly pigeon-toed shape.

    I am disappointed that it’s range does not extend this far west although this site shows a sighting this past June at Fort McMurray (where nothing is real) and none in Manitoba!) You might want to enlighten them.

  4. Ah, you’ve managed to hit another on my “maybe one of these days” list – they are so very lovely.
    Did find a Cecropia cocoon ‘way back when I was in Guides… When it finally emerged, all crinkly and tousled, that was a completely amazing thing to see. Not as showy as your Luna, but incredibly beautiful regardless and SO big! Truly awesome!!

  5. Oh, you’ve hit a nerve! Moths are a favorite of the insect species for me — more so than the beautiful butterfly. Especially the silk moth family. You might like this post (http://wp.me/p28k6D-tU) which has links to a few more videos of my kids and moths in another blog. FUN!

    • Thanks, Shannon. I’ve always been a fan of moths too. I think I always tend to root for the underdog 🙂 Thanks for the link. I look forward to checking it out. Have a great day!

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