Mourning Cloak Meetings

The Mourning Cloak butterfly (Nymphalis antiopa) Photo credit to Jacy Lucier on Flickr

The car swerved slightly to avoid squashing the tiny creature, crediting both the driver’s sharp eye, and her compassionate nature. I was impressed the wife even saw the tiny, insignificant caterpillar on the vast expanse of pavement. The little Nymphalis soldiered on across the road, unaware of its near existence ending encounter, as the Honda rapidly vanished into the distance.

It all started when Bob Richards paused, garden hose in hand, to water the soil around the willow saplings he’d planted a few weeks before. He was blissfully unaware of the butterfly approaching from downwind. The scent of fresh willow had been detected by the egg-laden female Mourning Cloak as she battled against the breeze that carried it to her. As Bob carried on watering his new gardens, the butterfly made it’s landing and started laying eggs around the stems of the fresh crisp leaves.

The willow sapling provided well for the initial stages of the larvae’s development. The Mourning Cloak hatchlings worked together, building a communal web to protect themselves. Under the safety of the web they passed 2 instars (moultings) until the food supply ran out. They set out, one after the other, in a “follow the leader” style until they came across another willow sapling (that Bob had planted). There, another web was communally constructed and they completed 2 more moultings. Unlike some other types of butterfly larvae, the Mourning Cloak’s larvae aren’t cannibalistic. For that reason, Mourning Cloaks can sometimes become a pest of landscaped yards (as Bob was about to realize).

One sunny, warm afternoon, Bob’s labrador retriever, Rex, sidled up to the sapling and relieved himself. His leg hit the small tree’s trunk causing a sudden jarring of the larvae’s world. They all vibrated rapidly and simultaneously to startle or frighten off the threatening creature. It worked very well, as not a single caterpillar was lost to the relieved canine.

A cluster of Mourning Cloak larvae. Photo credit to Jacy Lucier on Flickr

By the 5th instar, the caterpillars were as mature as they would become at that stage of their lives. It was time for “the big run”. This is when caterpillars forget about feeding for the first time in their lives, and simply run in search of a safe place to form a chrysalis. It’s assumed they run away from their food plant to get away from any droppings that might attract predators while defenseless in their chrysalises.

They all climbed down the tree trunk and headed off in different directions, leaving Rex to be blamed for killing the saplings with his incessant peeing. Some caterpillars headed across the barren lawn toward the forest where they were mostly consumed by everything from other insects to birds, rodents, and fungi. Others came upon the East fence which they climbed and prepared to form chrysalises. Some hit the dry patch above the septic tank where the grass hadn’t taken yet. The dry sand desiccated their sensitive bodies, and they perished in the sun. Then there was our girl. She headed due West, crossed the (fortunately dry) ditch, and onto the hot, dry pavement where she was narrowly missed by the gray Honda populated by Bushwhacker and the wife.

Once across the road, she found a long expanse of cool green grass with an odd fresh chlorophyll scent and wet, sappy tips. She ambled into taller grass, while a distant roar became louder and louder as it approached. It wasn’t as quick as that Honda shadow on the hot, dry, smelly black stretch, but it was considerably louder. She attempted to scramble to safety and silence, but the Lawn Boy simply overran her. As the sky darkened and the sound became deafening, our little heroine, missed by the blades, was picked up by hurricane-force air currents and thrown across the yard. Her tiny coiled (in protection position) little body bounced off the shed wall and landed on the patio stone base.

She held the defensive position a few seconds longer, just to “be sure”. Then she uncoiled and continued running. As the drone of the wind-beast faded into the distance, she hurried along the bright white surface of the patio stones, through the open shed door, and into the cool darkness. She climbed up an odd smelling wall onto a smooth, slippery surface, where her feet stuck regardless, and she began to search for a nice private place to sleep. Before she could settle in and begin, Lori Williams stepped into the shed, saddled-up the ATV and with a turn of the key, the monster roared to Life. The fumes and racket rivalled the wind-beast, and our little lady ran for cover. She found a crease in the fender to hide in as the ATV bounded out of the shed.

Mourning Cloaks will feed on nectar as well as tree sap. Photo credit to Jacy Lucier on Flickr

Lori was headed over to her friend’s house through the backwoods trail she’d run since early childhood. With a quick wave to her Dad on the riding mower, she cut across the freshly mown lawn and into the woods. The ride was rough and confusing for our little nymphalis, but she held on a best she could as the World flashed bright, dark, up, and down. As the ATV jumped a man-made “thrill – hill”, she was thrown off, and landed on the forest floor. The ATV roared away down the trail, and all became silent again. She held her coiled protective position for a few seconds, then opened up, and continued running.

The trail was wide, but she eventually made her way to it’s edge. There, she climbed up a granite boulder a glacier had dropped 10,000 years earlier in a field a kilometer away. 9,800 years later a farmer lifted, and dragged it to the edge of his field. On a broken branch resting on that boulder, she made her final stand. She gripped the branch with her furthest back legs, hung herself below, formed a “J” shape with her body and began the process of pupation. Within hours, she had transformed into a rigid, solid, unrecognizable form of herself where she stayed for 2 weeks.

Side Note – Of all the mysteries presented to Mankind, metamorphosis has never been explained. To this day, Science has no idea how it works. We’ll search for the sub-atomic boson which might explain quantum “mass” using huge particle accelerators costing trillions of dollars over decades of time … but we can’t figure out how caterpillars become butterflies in two weeks.

After two  quiet weeks of metamorphosis, our lovely lady crawled out of her chrysalis looking not quite lovely yet. However,  as she pumped blood into her folded up wings, they opened, revealing the rich chocolate base with solid gold and iridescent spotted blue trim of her species. She turned to face the sunny patch on the edge of the trail, picked up the scent of sap oozing from a wound on a nearby elm, and launched herself into the air. The only witnesses to this miracle was a disinterested chipmunk and a very interested (yet fortunately too distant) mantis. After a quick feed of tree sap (Nymphalis butterflies don’t drink nectar as much as tree sap), she fluttered away across the clearing into the adjoining field, never to return.

Aromatic fruit attracts Mourning Cloaks as well. Photo credit to Jacy Lucier on Flickr

Over the remainder of the Spring she had many adventures. An encounter with a robin left her wings tattered, a close brush with a dragonfly cost her a leg, but when the assassin bug leapt at her, she produced an audible “Click! “ which distracted the assassin enough to allow an escape.  Then, she had (yet another) meeting with that gray Honda up on County Rd #9 this time. Fortunately, the wife saw her at the last second and swerved (slamming Bushwhacker against the car door). They damn-near put the car in the ditch, but it was worth it ‘cause they missed her. Then, as the Summer approached, hot and dry, she found a flap of tree bark to hide in, reduced her metabolic rate, and passed the Summer in estivation (a type of hibernation prompted by conditions of heat and drought).

She emerged again once the heat passed, to enjoy the last of the season’s bounty of tree sap and the added treat of rotting apples. Inevitably, the days began to shorten and the nights became cooler. So she began the search for a site to pass the Winter in true hibernation. Nymphalis butterflies are one of the few which can hibernate as adults in Southern Ontario’s climate. She checked hundreds of possible locations before settling on a shallow cavity left by a broken tree branch just down toward the lake near the nickel tunnel bridge. As she “slept”, Southern Ontario endured the worst Winter in recent memory. Bitter cold, damaging winds, record snowfalls and … the ice storm.

Bushwhacker and the wife tried to walk some bush trails but they were still under a lot of ice with inches of snow under that. So they took to the roads. At least they were plowed and heavily salted/sanded. It was April Fools day 2015 and the wind was calm on a still cool morning. The sun promised to bring a taste of what the next weeks would bring. Bushwhacker wondered what had caused the two inch deep holes in the pavement. Then he realized he was standing on sand saturated ice, and the holes were caused by chunks of rock salt which had melted down to the pavement. Spring had a long way to go yet.

As they approached the nickel tunnel bridge something caught their eyes simultaneously . They shouted “Mourning Cloak!” together, and stopped to watch it. She fluttered up and over the bridge in search of a mate to start the cycle all over again.  All the while, neither butterfly nor Bushwhacker & the wife realized how familiar they all were, with each other.


With the obvious exception of certain “story-enhancing” specifics such as Lori Williams’ ATV ride, this story of our little mourning cloak’s life is factual. Mourning Cloak larvae are amongst the few caterpillars which will not cannibalize each other, but will work together for mutual survival. They actually do estivate (hibernate) through the heat and drought of Summer to emerge again in the cooler,  wetter Autumn. They are also true adult hibernators during the Winter months. This capability makes them one of the longest lived butterflies on Earth (9 – 11 months), though they’re “asleep” for a lot of that lifespan. This adult hibernation period, combined with their tree sap diet (sporadic flower nectar feeders), explains why they’re often seen fluttering over the snow in March long before other butterflies or flowers show up.

I can personally attest to the aggressive nature of the male of this species as I’ve been “buzzed” by them. I have also clearly heard the “click” sound they will make when either attacking an interloper or trying to distract a predator, allowing escape. They’re also very old lifeforms. Recent research into their evolution explains why these butterflies are “indigenous” to both the Western hemisphere and the European continent. Science now believes these same butterflies evolved during a time when all the continents on Earth were massed together in one Super continent  (termed Pangea) about 300 million years ago. That means not only were they fluttering around the dinosaurs heads, they managed to survive the great extinction event at the end of the Cretaceous Period, which the dinosaurs failed to do.




  1. I found your blog searching for an answer as to why a mourning cloak caterpillar hanging in a J position from my porch roof would be oozing a black liquid from it’s side. It’s wiggling and twisting like it’s in distress. Any ideas?


    1. I’m sorry to hear about your mourning cloak Gloriadelia. By your description, I suspect it’s infected with a bacteria (pseudomonas) or a virus (NPV).



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