Armadillidium Isopods: The Complete UK Guide to Pill Bugs and Roly-Polies

If you've ever turned over a stone in a British garden and watched a small grey creature curl into a perfect ball, you've met the genus Armadillidium. They're the original "pill bugs," the classic "roly-polies," and arguably the most beginner-friendly group of isopods you can keep. They've also become one of the most diverse genera in the modern hobby, with selectively bred colour morphs commanding eye-catching prices alongside hardy native species you can find in your back garden for free.

This guide covers what Armadillidium isopods actually are, the species and morphs commonly kept in the UK hobby, their care requirements, and how to choose the right one for your goals. It also corrects a few persistent inaccuracies that have circulated in older care articles online.

Quick Answer: What Are Armadillidium Isopods?

Armadillidium is a genus of terrestrial isopods (woodlice) in the family Armadillidiidae. They are native to Europe, the Mediterranean basin, and parts of North Africa and the Near East, with several species naturalised across North America, Australia, and beyond. They are best known for their ability to conglobate — roll into a tight, defensive ball — which distinguishes them from "false" pill bugs that cannot fully roll up. Adults typically reach 10–20 mm. They are generally hardy, undemanding, and well-suited to UK indoor temperatures, making them one of the most accessible groups for beginners and one of the most rewarding for collectors of designer colour morphs.

Where Armadillidium Actually Come From

This is worth getting right, because older guides — including the original version of this article — have repeatedly placed Armadillidium species on the wrong continent.

The genus is European/Mediterranean in origin. The most familiar species worldwide, Armadillidium vulgare, is native to the Mediterranean basin and southern/western Europe. It has been introduced and naturalised to North America (where it's now the most common woodlouse and is widely called the "common pill bug"), Australia, parts of South America, and elsewhere — but it didn't originate there. Calling A. vulgare a North American species is a bit like calling the grey squirrel an English one.

Other commonly kept species are even more localised:

• A. klugii — Croatia, Montenegro, and the Adriatic coast
• A. maculatum — southern France and the western Mediterranean
• A. gestroi — Italy
• A. granulatum — southern Europe and the Mediterranean
• A. werneri — wait, that's Porcellio. (Easy mix-up — Armadillidium and Porcellio are different genera in different families.)
• A. nasatum — western Europe, including the UK (often found in greenhouses)
• A. pictum and A. depressum — both native to parts of the UK, with A. pictum of conservation interest

The British Myriapod and Isopod Group (BMIG) maintains the authoritative checklist of Armadillidium species recorded in Britain and Ireland, with distribution maps and identification notes for anyone interested in the wild ecology behind the hobby.

What Makes Armadillidium Different

Several traits set this genus apart and explain its popularity:

True conglobation. Members of the family Armadillidiidae are "true" pill bugs because they can roll into a complete sphere when threatened. The hard, segmented exoskeleton tucks together with no visible gap — protecting the soft underside and reducing surface area for water loss. Many other isopods (such as Porcellio and Oniscus) cannot fully roll up and rely on speed or chemical defence instead.

Hardy, forgiving husbandry. Most Armadillidium species tolerate UK room temperatures (18–24°C) without supplementary heat, and they're less humidity-sensitive than tropical Cubaris or Vietnamese Ardentiella. This makes them ideal for new keepers and reliable in bioactive vivariums.

Visible behaviour. Compared with shy cave-dwelling species, Armadillidium are reasonably active on the surface, especially after misting or during cooler evenings. You actually see them.

Selective breeding potential. A. vulgare and A. maculatum in particular have produced an astonishing range of colour morphs in the hobby — from monochrome "high yellow" lines to multicoloured selectively bred patterns like Magic Potion. This makes them one of the most actively collected genera among advanced hobbyists.

Popular Armadillidium Species in the UK Hobby

Armadillidium vulgare — Common Pill Bug

The classic woodlouse of British gardens (in the south, at least) and the foundation species for almost every Armadillidium colour morph in the trade. Wild-type animals are mottled grey to dark brown; selectively bred lines include high-yellow, orange vigour, dalmatian, punctatum, and the spectacular Magic Potion. Hardy, prolific, and tolerant of mistakes — the ideal first species for any new keeper. For colour-morph keepers, our Magic Potion isopod care guide covers the specific husbandry that brings out the strongest colouration.

Armadillidium maculatum — Zebra Isopod

Native to southern France and the western Mediterranean. Distinctive black-and-white striped patterning makes them one of the most recognisable isopods in the hobby. Easy, prolific, and reasonably priced — typically the first "fancy" isopod people add to a collection beyond plain greys. There's also a striking white morph (A. maculatum "High White") for keepers who want something more unusual.

Armadillidium klugii — Clown Isopod

A genuine showstopper, native to Croatia and Montenegro. Despite occasional older descriptions calling them "brownish-grey," A. klugii is in fact one of the most colourful Armadillidium species — particularly the "Montenegro" line, which displays dark bodies edged with bright red "skirts" and scattered yellow or cream spots. They're more humidity-sensitive than vulgare but otherwise straightforward. Often listed as one of the top three "must-have" Armadillidium species alongside Zebra and Magic Potion.

Armadillidium gestroi — Milky Way Isopod

An Italian native, with the famous "Milky Way" line developed in the UK by breeder Jennifer Gosling. Speckled black-and-white patterning gives the appearance of a starfield against a dark sky. Easy to keep at room temperature with moderate humidity.

Armadillidium granulatum — Granulated Pill Bug

Mediterranean and southern European, not North American (despite some older articles getting this wrong). One of the larger Armadillidium species. The wild-type displays a distinctively granulated dorsal texture and yellow lateral spots, with various selectively bred colour lines now in circulation. Adaptable and hardy — see our dedicated Granulatum care guide.

Armadillidium peraccae — Peraccae Isopod

Italian species, smaller than vulgare, and prone to climbing. Generally easy to keep but require an escape-proof enclosure. Our Peraccae-specific care article covers the specifics.

Armadillidium versicolor

Balkan native (Croatia, Montenegro, and surrounding areas), known for an attractive iridescent or variable colour pattern depending on the line. Less common in UK collections than the species above but increasingly available.

Armadillidium nasatum — Peppered Pill Bug

An interesting one for UK keepers because A. nasatum is actually native to (or long-naturalised in) the UK — particularly common in greenhouses and warm urban environments. Smaller and more elongated than A. vulgare, with a distinctive nose-like projection on the head. Rarely kept in captivity simply because it's everywhere already, but worth identifying if you're collecting from a garden.

Armadillidium flavoscutatum "Redhead"

Albanian native with a distinctive red-orange head against a darker body. Tolerates lower humidity than most Armadillidium, making it easy to maintain. Increasingly popular in bioactive setups.

Armadillidium beieri

A rarer collector species occasionally available in the UK. Compact, with attractive colouration. One for keepers expanding beyond the basics.

Selectively Bred Colour Morphs

A separate category worth understanding. These are not new species — they are colour lines selectively bred from A. vulgare (mostly) over many generations to express particular pigmentation:

• Magic Potion — multi-toned colouration with significant individual variation; one of the most prized vulgare lines in the UK
• Vulgare Gem Mix — mixed selectively bred vulgare colour morphs sold as a starter blend
• Punctatum — heavily spotted "dalmatian" pattern
• Orange Vigour / High Yellow — uniformly bright orange or yellow individuals
• Maculatum "High White" — selectively bred white-dominant Zebras

Because these are all the same species, they will interbreed. If you want to maintain colour stability in your lines, keep each morph in its own enclosure and don't mix them — hybrid offspring tend to lose the selectively bred patterning over a few generations.

Armadillidium Care: The Essentials

The genus is forgiving, but a few principles apply across nearly all species.

Enclosure

A 5–20 litre plastic tub with a tight-fitting, mesh-vented lid is ideal for most starter colonies. Glass terrariums look attractive but lose humidity faster. Armadillidium climb less than some genera, but the lid still needs to be secure — small juveniles can squeeze through tiny gaps.

For more on enclosure setup, see our guide to setting up and selecting your first isopods.

Substrate

A 5–8 cm layer of substrate, deeper for species that burrow heavily:

• Coir or organic topsoil base
• Crumbled white-rotted hardwood (oak, beech, alder)
• Generous leaf litter top layer
• Sphagnum moss patches at the damp end
• Small pieces of cork bark for hides

A piece of cuttlebone or limestone is essential — Armadillidium require calcium for their thicker exoskeleton far more than thin-shelled species do.

Temperature

18–24°C suits most species year-round. UK room temperature is generally adequate without supplementary heating. Some Mediterranean species (like A. klugii or A. granulatum) appreciate the warmer end of the range, particularly for breeding. For the full picture on managing temperature, see our isopod temperature range guide.

Humidity

60–75% with a moisture gradient is the sweet spot for most species. Armadillidium tolerate drier conditions better than Cubaris but still need a damp end and a humid retreat (a sphagnum moss patch works perfectly). Mist one end of the enclosure every 3–4 days; leave the other end drier. Our complete humidity guide for isopods explains the gradient setup in detail.

Diet

Armadillidium are detritivores with broad appetites:

• Base food — leaf litter and rotting hardwood, always available
• Vegetables — small amounts of courgette, carrot, sweet potato every few days
• Protein — fish flakes, gammarus shrimp, or bloodworm twice weekly
• Calcium — cuttlebone or crushed limestone always available

Remove uneaten fresh food after 24 hours to prevent mould.

Breeding

Armadillidium are pouch-brooders. Females carry developing embryos in a marsupium on the underside of the body until they emerge as miniature mancae. Under good conditions, a colony will produce a new generation every 4–6 months, and juveniles reach breeding age around 6–10 months later.

Healthy Armadillidium colonies can grow rapidly — particularly A. vulgare and A. maculatum. Plan for eventual enclosure upgrades or colony splits. If your colony has stalled, our breeding troubleshooting guide covers the most common causes.

Wild-Caught Armadillidium in the UK

If you live in southern England, A. vulgare is genuinely abundant in gardens, churchyards, and limestone areas, and there's nothing illegal about collecting modest numbers from land where you have permission. A. nasatum is similarly common in greenhouses. Both make excellent starter colonies for new keepers and provide the genetic base for any selectively bred line you might develop yourself.

For the responsible approach to collecting — including legal context, quarantine, and the species worth picking up — see our guide to collecting isopods from the wild to breed in captivity.

Why Armadillidium Are Ideal for Beginners

If you're new to the hobby, Armadillidium gives you almost everything in one genus:

• Wide species range, from £5 starter colonies to premium designer morphs
• Hardy at UK room temperature without specialist equipment
• Visible enough to enjoy as display animals
• Productive enough to grow real colonies in reasonable timeframes
• Available wild for free in many UK gardens

For a fuller introduction, our complete beginner's guide to keeping isopods in the UK walks through species selection, equipment, and first-year goals.

Frequently Asked Questions

Are Armadillidium isopods native to the UK?

Several species are. Armadillidium vulgare is common across southern England, A. nasatum is widespread in greenhouses and urban habitats, and A. depressum and A. pictum are found in specific regions of Britain. Most other species in the hobby (A. maculatum, A. klugii, A. gestroi, A. granulatum) are continental European in origin.

What's the difference between Armadillidium and Cubaris?

Both can roll into a ball, but they're in different families. Armadillidium (family Armadillidiidae) are mostly European, hardy, and tolerate room temperature. Cubaris (family Armadillidae — confusingly similar names) are mostly Southeast Asian, often cave-dwelling, and require warmer temperatures and higher humidity. Armadillidium are generally easier and cheaper.

Are Armadillidium good for bioactive vivariums?

Yes — particularly A. vulgare and A. maculatum. They're effective detritivores, tolerate the conditions in most reptile vivariums, and breed reliably enough to maintain a self-sustaining cleanup crew.

How long do Armadillidium isopods live?

Adults typically live 2–3 years under good conditions, with some individuals reaching 4 years or more. They reach breeding age at around 6–10 months.

Can I keep different Armadillidium species in the same enclosure?

Different species generally won't interbreed and can coexist, but mixing creates monitoring difficulties and can introduce competition for hides and food. Different morphs of the same species (e.g. Magic Potion and standard A. vulgare) will interbreed and should be kept separately if you want to preserve colour lines.

Where can I buy Armadillidium isopods in the UK?

Browse our Armadillidium isopods for sale collection — every animal is captive-bred in the UK, with species ranging from £5 starter Zebras up to premium vulgare morphs.

Final Thoughts

Armadillidium may not have the headline-grabbing rarity of a Rubber Ducky Cubaris or the explosive colouration of Ardentiella (formerly Merulanella), but as a genus they offer something more important: reliability. They're the species new keepers learn on, the species seasoned keepers come back to when they want a productive bioactive crew, and the species selective breeders use to develop the most striking colour morphs in the hobby.

Whether you want to start with a £10 colony of Zebras, build out a serious vulgare morph collection, or simply identify the woodlice in your back garden, the Armadillidium genus is one of the best gateways into the wider isopod world.

Browse our full range of captive-bred Armadillidium isopods — or for an overview of every genus we work with, see our complete isopods for sale page.