Why are butterflies flying even in winter? — The 'Eternal Summer' practiced by the Itami City Museum of Insects and the 365 days of its keepers (Former professor, 846th day of retirement)

In pursuit of the king of the world's largest beetles: The challenge of the Bug Boys

It was a little while ago, but on the Yomiuri TV program 'Tokoro-san no Me ga Ten!', there was a special feature where the insect enthusiast group 'Tokyo Bug Boys' conducted a massive search in the forests of the Ecuadorian Amazon in search of the world's largest beetle, the 'Hercules beetle.' Their goal was to discover the wild Hercules beetle of their dreams, which they had only ever seen in picture books. The members expressed their burning passion, saying, 'We can't go home without finding this.' During the first half of the search, they were excited to catch giant 'longhorn beetles,' but they couldn't easily find the Hercules beetle they were looking for. On the final day, they climbed to an altitude of 1600 meters and identified the habitat of the 'Koruka tree,' known for being a place where Hercules beetles suck sap. And late at night, they finally discovered a wild Hercules beetle. The members expressed their joy through tears, saying, 'It really existed' and 'I'm so happy to see a creature I've only ever seen in books.' The specimen found was 13 cm long and had two long horns and golden hairs that act as non-slip grips. When placed on their hands, it clung on powerfully, and its sharp claws dug in. Even so, they felt the life force of the Amazon firsthand, saying, 'It's okay if my hands get torn up.' I have also loved beetles since I was young, and searching for beetles and stag beetles was a daily routine during my summer vacations as a boy. Since this trip was, so to speak, a search for the 'king of beetles,' I understood their feelings well. (Please also see the photo below)

The keepers of the Itami City Museum of Insects and Hiyori Katada show their deep love for insects

On the other hand, my wife apparently liked butterflies, not beetles (Wife's addition: To be precise, I liked 'butterfly larvae'). When I asked her about it, she said that when she was little, she would collect swallowtail butterfly eggs laid on the yuzu tree in her garden, bring them home, and hatch them. Swallowtails lay their eggs on soft new shoots. She laughed, saying that because she collected them all, she was scolded by her father, who was carefully raising the yuzu tree. So, this time, the topic is not beetles, but 'butterflies'.

I watched a special feature on the 'Itami City Museum of Insects' on NHK's 'The Backyard.' The reporter is actress Hiyori Katada. She is actually quite an insect geek, and it seems she is a charismatic figure among insect lovers, sharing the charm of insects on social media. Even within the program, she fully unleashed her love and knowledge of insects (laughs). Since opening in 1990, the Itami City Museum of Insects has been affectionately known by locals as 'Itakon.' The museum's exhibits go beyond mere specimen displays, focusing on interactive installations and the reproduction of ecological environments. In the '10x Forest,' the natural environment near Itami is recreated, and not only famous insects like the Great Purple Emperor and the Great Blue Mime are introduced, but also inconspicuous insects like burying beetles and leaf-rolling weevils are shown at 10 times their size, conveying that diverse organisms support the ecosystem. There is also a huge, precise model of a honeybee called 'Big Bee,' made at 200 times the scale of the real thing. Even the body hair and pollen baskets, which are difficult to see with the naked eye, were precisely reproduced. Ms. Katada said she used to play here when she was a child, and she looked at it with nostalgia. (Please also see the photo below)

The professional persistence that supports one of the largest 'butterfly greenhouses' in the Kansai region behind the scenes

And the biggest highlight of the Itami City Museum of Insects is one of the largest 'butterfly greenhouses' in the Kansai region, where about 1,000 butterflies of about 14 species fly around all year round. Ms. Katada was moved by the sight of butterflies flying that are rarely seen in the city, and she enjoyed taking photos while observing the courtship and egg-laying behavior of species like the Chestnut Tiger and the Tree Nymph butterfly up close. However, there was an extraordinary effort by the keepers hidden behind the scenes to exhibit butterflies, which have short lifespans in the natural world, all year round. (Please also see the photo below)

Insects usually feel winter when daylight hours shorten and temperatures drop, leading them to hibernate, or overwinter. However, the museum's breeding room is kept in a 'summer environment' with a temperature of 25 degrees Celsius and 16 hours of daylight. Therefore, the butterflies continue to breed without feeling winter, and they can emerge every day throughout the year. In the breeding room, eggs laid on the host plants in the greenhouse are collected every evening, strictly identified by species, and sorted into cups. Since some species, such as the Yellow Orange Tip and the White-spotted White, lay eggs on the same host plant (photo above, bottom right), careful work is required. There are always over 500 larvae and pupae in the backyard, and health management such as cleaning feces, changing food, and checking for diseases was continued 365 days a year without a break. For example, when a pupa emerges, meticulous care is essential, such as creating a foothold with a tissue so that it can easily spread its wings. (The title photo shows a larva that releases its osmeterium when touched: Note 2) (Please also see the photo below)

Even more important is securing the 'host plants' to raise the butterflies. Butterfly larvae only eat specific plants depending on the species. Moreover, many of these plants are not commercially available, and there are no cultivation manuals. Therefore, the keepers themselves cultivated many types of host plants without pesticides. For example, citrus fruits, which are food for swallowtails, cannot be eaten by larvae immediately after hatching because the leaves are too hard. Therefore, they manage them in pots in a dedicated greenhouse, pruning them to produce soft new shoots, and so on, putting effort into the growth environment of not only the insects but also the plants.

The 'ex-situ conservation' of the Itami City Museum of Insects that connects the future of endangered species

The Itami City Museum of Insects is also working on breeding rare insects, not just butterflies. For example, it also targets extremely rare insects such as the blue longhorn beetle, which lives in only one place in Japan. There are many types of such insects whose ecology is not fully understood, and it sometimes takes several years, including field surveys, to establish breeding methods. And attempts were also being made to return the bred individuals to their original habitats and have them re-establish themselves (photo below, bottom left). Also, by managing and breeding the Ogasawara tiger beetle, which is endemic to the Ogasawara Islands, from the larval stage, the museum is said to have one of the top track records in Japan for the conservation of rare insects. (Please also see the photo below)

Behind its vibrant exhibits, the Itami City Museum of Insects plays two vital roles: meticulous environmental management that enables year-round butterfly breeding, and 'ex-situ conservation' to secure the future of endangered species. I gained a deep appreciation for the profound knowledge, affection, and steady dedication of the keepers who watch over not just the insects but the plants as well, connecting lives without a single day of rest throughout the year. Until next time.

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Note 1: From the Yomiuri TV program 'Tokoro-san no Me ga Ten!' special feature 'The Great Hercules Beetle Search'
Note 2: From the NHK program 'The Backyard' special feature 'Itami City Museum of Insects'