A Moment and a Lifetime: A Summer with the Great Purple Emperor

I have compiled the story of the day I met a Great Purple Emperor in the forest on a hot summer morning.
This article is an observation record based on a short report note published on Jxiv (DOI: 10.51094/jxiv.1535).

My First Encounter with a Great Purple Emperor

In the Konara oak forest, a single tree with plenty of sap was swarming with beetles and hornets. Among them, a female Great Purple Emperor was spreading her wings wide. I could hardly believe my eyes as she sipped the sap while skirmishing with a scarab beetle. I clicked my camera shutter repeatedly, asking myself over and over, "That's a Great Purple Emperor, isn't it?"

Suddenly, the female disappeared. She had left the sap-producing tree and flown to a nearby tree that had no sap.

The thought crossed my mind that it might have been only a fleeting encounter. When I wished for her not to leave, she repeated the action of returning slightly and then flying away again.

Thinking she might be a teasing butterfly that leads people astray, I turned back to the sap tree, and there was a male with shimmering blue wings. Then, the female landed gracefully beside the male. The one she was teasing was not me, but the male behind me.

The Beginning: The "Great Purple Emperor Overwintering Larva Observation Meeting"

It was in February that I was invited to the "Great Purple Emperor Overwintering Larva Observation Meeting." It was only after participating that I learned there are larvae that hibernate in the fallen leaves of hackberry trees. Moreover, I was told there was a possibility that three types of larvae were sleeping there. I was shown photos of the larvae and adults of the Great Purple Emperor, the Japanese Emperor, and the Asian Comma. I had seen the adults of the Japanese Emperor and the Asian Comma in the field before. However, I had never encountered a Great Purple Emperor. I wondered why I had never met such a colorful and large butterfly. According to those who have seen the Great Purple Emperor, it is a butterfly that flies with a powerful, flapping motion.

Participating in this observation meeting sparked a sudden interest in the Great Purple Emperor, and I wanted to see one in the wild.

Research and Planning

First, I narrowed down the habitats of the Great Purple Emperor in the vicinity. From the places where larvae had been found and locations with past sighting reports, I narrowed it down to two spots within a 30-minute bicycle ride. If I could visit once or twice a week, the chances of an encounter should increase.

As a beginner, I wouldn't be able to find them unless they emerged as adults. I set the adult season to late June through early August, based on my online research.

When I listened to people knowledgeable about insects, they said that while they used to be commonly seen in the satoyama (rural landscape), they are now almost impossible to find. Furthermore, the points for finding them differ from person to person.

• They come to sap-producing trees to drink nectar.

• They often lay eggs on the leaves of young hackberry trees.

• They fly high up in the trees.

• Males have territories and fight with other males.

• They prefer sunny days.

Based on this information, I went out into the field from late May to look for locations, searching for sap-producing trees—such as Konara oaks and other acorn trees—and young hackberry trees. Places with many Konara oaks were easy to find, but I could not find any young hackberry trees.

From late June, I decided to focus my visits on the Konara forest and search during the morning on sunny days.

Observation session of captive breeding as mental training

If possible, I wanted to see the Great Purple Emperor flying in the wild.

There is a facility nearby that holds an observation session for the Great Purple Emperor every year, and I had been applying annually. However, it is extremely popular, and I had been rejected for four consecutive years.

Even before participating in the 'Overwintering Larva Observation Session,' I felt pathetic for having information about the Great Purple Emperor while still applying, but as a result, I was successfully selected.

The observation session involved netting around several hackberry trees, with over 100 Great Purple Emperors fluttering inside. The net was probably about 3 to 4 meters high. Seeing them flutter made me keenly aware of the difficulty of finding them in the wild. As butterflies, they fly large and dynamically, but the undersides of their wings are the same green as the leaves. I felt it would be extremely difficult to find them flying above a Japanese oak tree that is over 10 meters tall.

It was late June.

How to encounter the Great Purple Emperor

Before my full-scale search for the Great Purple Emperor, the captive observation session had left me feeling discouraged. Even when I found trees with sap, I couldn't see any butterflies when I looked up. I even tried going out in the evening when the morning didn't work. Still, there were no butterflies, and as the days of extreme heat continued, the appearances and sounds of other insects and birds also decreased.

Until the season ended, I decided to treat even the days without encounters as data and savings for next year and beyond.

I felt confident that they must be living nearby precisely because I had seen the overwintering larvae.

A gift from the Great Purple Emperor

On July 30th, thinking that today might be my last chance to encounter the Great Purple Emperor this year, I went to the field where I had found the overwintering larvae. If this year didn't work out, there would always be next year. I walked in a resigned mood, thinking of the many animals and plants I had encountered only after several years of searching.

On a mountain path where people rarely pass, spider webs hit my face repeatedly.

And finally, I encountered a female Great Purple Emperor. A male followed, and I was able to capture a photo of the two of them together.

I was excited and wanted to shout, 'Thank you for the best gift!'

Watching the male take up a position near the female Great Purple Emperor as she calmly drank sap, I suddenly thought: with a male and female so close together, it wouldn't be strange if they started mating. The male was constantly moving behind the female. The female would occasionally show signs of being bothered by the male, but she was absorbed in competing with the flower beetles for the sap-oozing spot.

The moment I looked down, thinking that mating wouldn't start so easily, the sound of the Great Purple Emperors flapping their wings echoed, and two of them fell to the ground, joined together.

The female was flapping her wings while still joined. The male remained connected to the female with his wings firmly closed.

They kept thrashing on the ground and then resting, over and over. It had been going on for more than 15 minutes. I looked up online how long mating takes. It seems it takes at least 4 to 5 hours, and can take as long as 10 to 20 hours.

It was another hot day, exceeding 30°C. Since I had run out of the water I brought, I decided to head home for a while. Even after I got home, I was worried about the Great Purple Emperors. There must be birds and mammals in the forest that prey on them. I couldn't help but worry that if they kept thrashing around so loudly, they would be found, or that someone might come along and step on them without realizing it. Thinking I would regret it if I didn't go back to check on them, I returned to the forest.

Even though I had just seen the spot that morning, it felt very far away. Especially when I approached the place where the Great Purple Emperors had been, I walked cautiously, afraid of stepping on them if they were still joined on the ground.

When I arrived at the tree where sap was oozing, a female Great Purple Emperor was drinking the sap. I said to her, 'I hope it ended safely. Good work.' Something moving above her caught my eye. It was a male Great Purple Emperor. Could it be the same couple I met this morning? A wave of emotion washed over me once again.

A week later, I went to the same place again to check. I didn't encounter any more Great Purple Emperors. Beetles were gathering around the sap in the always-quiet forest, and a praying mantis was waiting nearby.

Video of the Great Purple Emperor

Link to the Short Report Note

The observations in this article have been organized based on field record data, and published as a short report note summarizing behaviors, timeframes, individual characteristics, and more in detail.
You can view the research record (preprint version) from the link below.

🔗 A Moment and a Lifetime: A Summer of the Great Purple Emperor — Short Report Note (Jxiv)

By capturing the 'moment' felt in the field in the 'form' of a record, I believe it will lead to future observations and comparative studies in other regions.
I believe this will lead to future observations and comparative studies in other regions.

Next Preview / Series Information

This observation record is part of a series documenting encounters with living things throughout the seasons.
In the future, I plan to gradually release more entries such as 'Once-in-a-Lifetime Encounters,' 'Scenes of the Season,' and 'Amidst the Presence,' incorporating observation data and record photos.

To find clues to ecology within a once-in-a-lifetime encounter.
And to re-examine the distance between nature and humanity.

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