A Glimpse
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Origin: Thailand (eastern Isaan region), also introduced to parts of Vietnam
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Scientific Name: Atopochetus spinimargo
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Related Species: Cousin of the Vietnamese Rainbow Millipede (Atopochetus dollfusii)
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Difficulty Level: Easy
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Adult Size: 8–10 cm
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Rarity: Uncommon in the UK hobby
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Temperature: 20–27°C
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Humidity: 65–75% — adaptable, not overly fussy
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Ventilation: Moderate
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Diet: Decaying leaf litter, rotting white wood, lichen, moss, vegetables, fruit, fish flakes
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Supplements: Cuttlebone, crushed limestone, or eggshell for calcium
Thai Rainbow Millipede: Overview
The Thai Rainbow Millipede is one of the more approachable species in the Atopochetus genus. It's a smaller millipede — adults top out at around 8–10 cm — but what it lacks in size it makes up for in colour. The body has contrasting orange and grey-green banding that catches the light nicely, especially under bright conditions. They're not as dramatically vivid as their Vietnamese cousin (A. dollfusii), but they've got a subtle, attractive look of their own.
They originate from the Isaan region of eastern Thailand, which is characterised by lush river landscapes and dense, humid rainforest. In captivity, they're one of the more forgiving species to keep, and they breed readily, making them a solid choice if you're newer to millipedes or want something that will actually establish a colony without too much hassle.
Keeping Them
The enclosure doesn't need to be enormous given their smaller size — a container with a floor space of around 30 x 30 cm will work for a small group. The key thing is substrate depth. These millipedes burrow down into the substrate to moult, and they'll need to disappear fully, so the substrate should be at least as deep as the length of an adult — roughly 10 cm minimum. A mix of organic compost, coconut coir, and crumbled rotten wood works well. Top it off with a generous layer of leaf litter and some pieces of white rotten wood.
Temperature-wise, they're not demanding. Room temperature in most UK homes (around 20–24°C) will be fine for much of the year, and they'll tolerate up to 27°C comfortably. You likely won't need a heat mat unless your house runs particularly cold in winter. Humidity should be moderate — keep the substrate damp but not waterlogged. They're more adaptable than a lot of tropical species in this respect and don't need it dripping wet.
One thing worth noting is that these are reasonably keen climbers. Their legs are a bit longer than you'd expect for a burrowing millipede, and they'll make use of cork bark, branches, and other climbing opportunities in the enclosure. Providing some vertical elements will keep them more active and visible.
Diet
This is one of the easier species to feed. Their main diet is decaying leaf litter and white rotten wood, which they'll graze on constantly. But unlike some specialist feeders, A. spinimargo will also accept a good range of supplementary foods — vegetables, fruit, lichen, moss, fish flakes, and even insect jelly. Carrot sticks seem to be a particular favourite based on what breeders report. This dietary flexibility is a big part of what makes them beginner-friendly.
As always, keep a calcium source available in the enclosure — cuttlebone, crushed limestone, or eggshell. This supports healthy exoskeleton development, especially during moults.
Temperament
These are calm, easy-going millipedes that can be handled without drama. Younger individuals tend to be more active at dawn and dusk, but as they mature they seem to gain confidence and will happily wander around during the day too, which is a nice bonus for display purposes.
Like all millipedes, they can produce a mild defensive secretion if they feel threatened — it's harmless but worth washing your hands afterwards as a matter of habit.
They're social animals and do well in groups. They can even be kept alongside certain other terrarium inhabitants like snails, if that's your kind of setup.
Breeding
One of the strong points of this species. A. spinimargo breeds readily in captivity and is considered prolific compared to many other millipede species. They can start reproducing from around 10–12 months of age. Eggs are deposited in the substrate, and the young are independent from hatching. Just make sure the substrate is deep enough for moulting and that there's always plenty of leaf litter and wood available for the growing colony to feed on.
Being Realistic
There's not a huge amount to warn about with this species, which is part of their appeal. They're small, they eat a varied diet, they breed well, and they're not fussy about exact humidity or temperature. If there's a downside, it's that their colouring is more understated than some of the flashier millipede species — if you're after something that screams colour from across the room, something like a Red Fire Millipede might be more your thing. But for a reliable, easy-to-keep species that will actually thrive and breed in captivity, these are hard to fault.
There's also some taxonomic confusion in the hobby around "Thai Rainbow" millipedes — you'll sometimes see Atopochetus caudulanus and even Apeuthes sp. sold under the same common name. A. spinimargo is its own distinct species, so if you're specifically after this one, make sure you're buying from someone who knows what they're selling.
