Armadillidium vulgare 'Magic Potion'

Armadillidium vulgare is a terrestrial crustacean in the order Isopoda, suborder Oniscidea, class Malacostraca. Not an insect — more closely related to crabs and shrimp than to anything with wings. The species is native to the Mediterranean region and has since spread across Europe, North America, and beyond. In the UK you know them as pill bugs or roly-polies. They live in leaf litter, under logs, in garden walls, and in damp soil — anywhere with moisture and decaying organic matter.

The 'Magic Potion' morph is where things get interesting. These have been selectively bred for a purple-grey body with orange or peach-coloured patches along the edges of their tergites (the segmented plates on their back). The contrast between the purple and orange is genuinely striking, and it is consistent enough to breed true once the line is established. Individual variation exists — some lean heavier on the purple, others show more orange. Both sexes carry the colouration, though gravid females sometimes appear slightly duller.

A. vulgare is the species that conglobates — it rolls into a tight, seamless ball when disturbed, tucking its legs and antennae completely inside. This is the defining trait of the Armadillidium genus and a reliable way to distinguish them from Porcellio, which cannot do it. They are calm, slow-moving isopods, much less skittish than Porcellio species. Colonies are steady rather than explosive growers. Expect a lifespan of 2–4 years with good care.

A. vulgare is a hardy species and a solid choice for someone keeping isopods for the first time. Magic Potions have the same care needs as wild-type A. vulgare — the colour morph does not make them more fragile.

Enclosure: A ventilated plastic tub or small faunarium. For a starter group of 10–15, a 20×15 cm footprint is the minimum — bigger lets the colony establish faster. Good ventilation matters: drill holes in the lid and ideally one side as well. Armadillidium prefer slightly drier conditions than many other isopod genera, and stale, humid air causes problems for them.

Substrate recipe:

• 60% coco coir
• 20% organic topsoil (no fertilisers or pesticides)
• 10% fine sand for drainage
• 10% crushed limestone or cuttlebone powder

The limestone in the mix is there for a reason. Armadillidium species have thicker, more heavily calcified exoskeletons than Porcellio, and they need a reliable calcium source to mineralise properly after each moult. Lay the substrate 5–8 cm deep and top with dried oak or beech leaves plus a piece of cork bark.

Temperature: 18–24°C. Normal UK room temperature. They tolerate cooler conditions down to about 12°C but will slow breeding and activity below 16°C. Don't place the enclosure on a windowsill or near a radiator — direct heat and sunlight dry them out fast.

Humidity: 50–70%. This species likes it drier than most. Keep one corner damp by misting with dechlorinated water every few days, and let the rest of the enclosure dry out. A moisture gradient is the goal: damp refuge at one end, dry ground at the other. If the entire enclosure is wet, you will lose mancae to drowning and bacterial issues.

Diet: Dried leaf litter is the foundation — always have oak or beech leaves in the enclosure. These are food, shelter, and a moisture buffer all at once. Add vegetable scraps a couple of times a week: cucumber, courgette, carrot, or sweet potato work well. Keep a piece of cuttlebone in the enclosure at all times for calcium. Once a week, offer a small amount of protein — dried shrimp, fish flakes, or a crushed dried mealworm. Go easy on protein. Overfeeding it attracts grain mites.

Social needs: Colonial species. Start with at least 10. They are not aggressive towards each other and do well in dense groups. Don't mix with other Armadillidium species in the same enclosure — hybridisation is possible and you will lose the morph.

Breeding: Females carry eggs in a marsupium (brood pouch). Mancae emerge as tiny, fully-formed copies of the adults, already showing hints of the purple and orange colouring. A. vulgare breeds more slowly than Porcellio species — expect new broods roughly every 6–8 weeks in warm conditions. Give the colony a few months to settle before expecting visible growth. A group of 15 can reach 40–60 within six months if conditions are stable.

Watch out for: Excess moisture is the main killer for this species. If the substrate feels soggy across the whole enclosure, add ventilation or let it dry out. Grain mites can appear if you overfeed or if fresh food sits too long — remove uneaten veg within 48 hours. White mould on leaf litter or cork bark is normal and harmless; green or black mould means conditions are too damp with too little airflow.

For the full species care guide, see our Armadillidium vulgare care guide.

Magic Potions are shipped in a ventilated deli cup with lightly dampened sphagnum moss, a small piece of cork bark, and a few leaves for cover. A. vulgare tolerates transit well compared to more humidity-dependent species — they cope with brief dry spells better than tropical isopods. The deli cup goes inside an insulated postal box with a heat pack or cool pack as needed for the forecast temperature.

We ship Monday to Wednesday via Royal Mail Tracked 24 to avoid parcels spending the weekend in a sorting office. If the forecast shows temperatures below 2°C or above 28°C, we will hold the order and get in touch to reschedule.

When your isopods arrive: Open the cup somewhere quiet and at room temperature. Gently tip the contents — moss, leaves, and isopods — into their prepared enclosure. They will likely conglobate (ball up) when first handled; this is a defensive response and completely normal. Leave them alone for a day or two. Mist the damp side of the enclosure lightly and let them explore in their own time. Avoid digging through the substrate to check on them during the first week.

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