Milionia Zonea: Entirely New Species of Moth or Back After a 400-year Hiatus?

It was on a particularly humid day in May 2024, that I spotted what I initially thought was a pretty intriguing-looking butterfly. Its wingspan was no larger than a human adult palm but it had a particularly vibrant curved band of orange on its wings.

Thinking nothing of it at the time, I lazily took a picture and promised myself I would try and identify this weird 'butterfly' that I had never seen before.

Perhaps a week later, I remembered that I still hadn't found out what species I had photographed. It was only after further research that I realized the butterfly was actually a moth known as Milionia Zonea.

I encountered another Milionia Zonea a few days later in a more natural setting and dug deeper to learn more about this elusive moth's history in Hong Kong.

Turns out, there's a split opinion on the origin story of Milionia Zonea.

One theory proposes that the moth used to inhabit Hong Kong some 400 years ago but mysteriously vanished until 2016.

The second theory Milionia Zonea was never native to Hong Kong at all and was brought over accidentally as part of the horticulture trade around 2016 - when sightings of the moth first began to emerge.

When looking into the natural geographic range of Milionia Zonea, I found that it includes the Northeastern Himalayas, Taiwan, Japan, Sundaland, and the Philippines. This means that Hong Kong certainly could have been part of the moth's natural range in the past, supporting theory one that Milionia Zonea might have just vanished for a long period of time while initially being a native species of Hong Kong. However, it's impossible to really know whether Hong Kong is within the moth's historic range for certain. This makes both theories hold weight.

While I, personally, was enamored by the beauty of Milionia Zonea, I found that many Hong Kongers actually aren't too fond of this new permanent resident of the city.

The larva of Milionia Zonea is known to consume the Buddhist Pine (Podocarpus macrophylla) in Hong Kong, often in groups that can defoliate entire trees. Since these trees are a valuable horticultural asset associated with good fung shui, Milionia Zonea caterpillars have garnered some negative attention. Podocarpus macrophylla trees are tremendously expensive in Hong Kong, with even small specimens costing thousands of HK dollars.

Ironically, it is probably while importing Podocarpus macrophylla trees that Hong Kong accidentally acquired its first specimens of Milionia Zonea caterpillars or eggs.

Another possibility is that the moths just flew over into Hong Kong from nearby regions of Guangdong, where Podocarpus macrophylla trees are growing in popularity and are being imported at a rapid rate.

Despite the defoliating behavior of Milionia Zonea caterpillars, Podocarpus trees possess the ability to regrow their leaves and will do so naturally, so there's really no reason to hate on these epic moths!

As far as moths go, Milionia Zonea is relatively large, with a wingspan of approximately 50 mm (2 inches). Its wings are adorned with a broad orange stripe that stretches across the forewing and extends along the hindwing. You will also notice what almost looks like a cute finger painting pattern on the bottom of the hindwings. The body of the moth will exhibit an iridescent blue hue when the light catches it just right.

Milionia Zonea is also diurnal, meaning that you can see Milionia Zonea during the day while most other moth species (even in this family of moths) are nocturnal. This makes it far easier to spot than other nocturnal moths, which may be more elusive unless you're a night owl.

The cool thing is that you can spot Miliona Zonea in wild and urban areas in Hong Kong, so keep your eyes peeled for bright flashes of orange! You might just be able to catch a glimpse of one of Hong Kong's most beautiful mysteries!