Armadillidium nasatum, the Nosey Pill-Woodlouse, ranks among the easiest Armadillidium to keep, and one feature reliably separates it from the common pill woodlouse: a raised plate jutting forward from the front of its head. Give it 18 to 24°C, which a heated room manages for most of the year, and an airy tub kept dry except for a damp third of the floor, with leaf litter and rotting hardwood to eat and a calcium source that never runs out. Below: origins, setup, breeding and the Orange (Peach), Dalmatian and White lines.
The Nose, and the Names
Budde-Lund named Armadillidium nasatum in 1885; nasatus is Latin for large-nosed. On the common pill woodlouse, A. vulgare, the front edge of the head is a low rim lying flat against the face. On A. nasatum a narrow, squarish plate stands up and juts forward between the antennae, which the British Myriapod and Isopod Group (BMIG) compares to the peak of a baseball cap. Many nasatum carry pale stripes along the back, but the stripes vary too much to go by.
BMIG calls it the Nosey Pill-Woodlouse, some American sources the nosy pillbug, and a 2019 key to the woodlice of Berkshire, Buckinghamshire and Oxfordshire the Striped Pill Woodlouse; most sellers just say nasatum. Touch one and it curls, but the ball never seals: the antennae poke out, and a narrow gap usually stays open between the head and the tail end, where A. vulgare shuts into a smooth sphere. BMIG and the German identification guide both describe this incomplete ball, so the gap is normal.
It is also the smaller animal. BMIG gives adults to about 12 mm, against 18 mm for A. vulgare, and the largest of 24 animals collected outdoors in the Netherlands in 1927 measured 11 mm. Hobby figures, mostly from sellers' listings, run a little larger, most often up to 14 or 15 mm, and the 12 to 16 mm on our care panels comes from a Dutch seller.
Where Nasatum Comes From
Its native range is south-western Europe, taking in Spain, Italy and the west and south of France, though how far north it reaches is not settled. People have carried it much further: it lives in glasshouses and towns across central and northern Europe, Germany's 2024 Red List says it is spreading more than any other introduced woodlouse there, and a 1969 study called it one of the commonest woodlice of the south-eastern United States.
In Britain it has been recorded outdoors in southern England since at least 1900: Webb and Sillem's 1906 book The British Woodlice lists it from Cheddar, Clifton and near Maidstone. BMIG now describes it as patchy across southern England and south Wales, on dry, sunny, sparsely vegetated ground such as coastal grassland, old quarries, railway lines and brownfield sites, where it shelters under stones and debris. It is not a typical garden woodlouse, and far less common than A. vulgare. It is also moving north, apparently with the horticultural trade: almost all of the most northerly records come from garden centres or glasshouses, and in 2023 a recorder found it under potted plants at every garden centre he searched in north-east England, south-east Scotland and Northern Ireland. Whether it is native has not been settled.
Outside Britain it is not tied to dry, sunny ground: in Virginia it lives in part shade around buildings, and in parts of France on sandy river banks.
Setting Up a Nasatum Tub
The care panels on our listings say 18 to 24°C; sellers' own figures vary, but almost every range takes in 21 to 23°C. An English home averages about 19°C over the heating season, so a heated room keeps nasatum inside our band for most of the year with no heat mat. If you want young through the winter, add a low-wattage heat mat or heat cable on a thermostat, fixed to the side of the tub and never underneath. In summer, keep the tub out of direct sun; our guide to how care changes from summer to winter covers what to do in a heatwave.
Our panels put humidity at 50 to 70 per cent across the whole tub, nearer 50 at the dry end and 70 at the damp end, but the layout matters more than the number: one end damp, a third of the floor or so, under moss or a slab of bark, and the rest dry, as most care sheets recommend. The 45 to 80 per cent one European seller quotes is a range to stay inside, not a target.
Vent the lid and two opposite walls, so air crosses the tub instead of settling in it. Wet, still air is the thing to avoid: the one colony loss we found reported was put down by its keeper to poor ventilation, with condensation dripping from the lid.
Nasatum barely burrows, so 5 to 8 cm of substrate will do: crumbled white-rotted hardwood, organic topsoil and flake soil, so the floor itself is food. Leave out coir, which keeps water well but gives a grazing animal nothing to eat. Heap hardwood leaves on top and lay bark flat, because the colony gathers underneath it. Start ten to twelve in a tub of 11 litres or more; a bigger tub holds its moisture better through a missed day or a hot spell.
Feeding and Calcium
Leaves and rotten wood are most of what it eats, so top both up before they thin out. Everything else is an extra: a sliver of squash or carrot now and then, fish flake or dried shrimp roughly weekly for protein, with anything untouched cleared before it moulds. Woodlice harden each new cuticle with calcium carbonate, so a cuttlebone or some crushed shell should never leave the tub.
One caution for bioactive keepers: several sellers say nasatum will eat soft live plants, and a university extension fact sheet notes reports of it feeding on cucumber plants and fruit. In a planted vivarium, you may see some damage to soft growth.
Breeding and Growth
The best field data come from Virginia, where Adamkewicz's 1969 study found two broods a year between June and late August and young maturing at about eight months. Indoors, opinion is split: some sellers and keepers call it prolific, while one keeper finds it nowhere near as prolific as the Zebra, A. maculatum, and another reports about a year from birth to adult. Give fresh stock a few months to settle before judging it.
The young are born colourless, with red eyes, and begin to show their colour at about two months, the same study found, so juvenile Orange or Dalmatian stock starts out plain. They leave the pouch with six pairs of legs, and the seventh pair grows in over the first three moults: three to four weeks at around 20°C in most woodlice that have been timed, nearer seven in A. granulatum, and nobody has timed it in nasatum.
If a tub runs heavy with females, there is a known cause: A. nasatum can carry a strain of Wolbachia, a bacterium that turns genetic males into females. In laboratory lines most infected mothers had mainly daughters, though some had only sons, and the population as a whole should settle near an even sex ratio (Becking and colleagues, 2019). How common it is in hobby stock is unknown, and the species still needs males to breed; our guide to Wolbachia and other isopod symbionts explains more.
Orange (Peach), Dalmatian and White
Orange. Reddish animals turn up in wild populations: the Virginia study covered wild red, dark and brown forms, with red mostly recessive, and French records note reddish and ochre individuals. Orange lines, also sold as Peach, have been started more than once, from orange animals found in cultures and at least once in an American garden. Most sources treat Orange and Peach as one colour under two names, though we found no published cross between them.
Dalmatian. A pale animal blotched with dark grey or brown. American shops mostly sell what seems to be the same form as Pearl, a name also used for paler, almost white animals. We could not find anything published on how the spotting is inherited in this species, and breeders argue about it; the part they agree on is that a line nobody selects slides back towards the wild type, so each generation has to be picked over.
White. Ours is pale cream with dark eyes, sold as a reduced-pigment line, though the albino in a 1984 breeding study of nasatum colours kept normal eyes, so dark eyes do not rule out albinism here; how our line arose has not been published. The name is used loosely: the White Out, sold mostly by American breeders, is white or off-white with white eyes, and one breeder describes it as a simple recessive. Check the eyes of grown animals when you buy, dark on our White and white on a White Out, though eye colour is a hint, not proof; our guide to telling white isopods apart explains why.
Keep one morph per tub if you want the colours to carry on. The lines are one species and interbreed, and most of the colours are thought to be recessive, so a mixed tub is expected to fill with wild-type-looking young. We found no record of nasatum crossing with A. vulgare, though the two often share ground in the wild; there is still no reason to share a tub.
Frequently Asked Questions
Is Armadillidium nasatum native to the UK?
Nobody can say for sure. It has been recorded outdoors in southern England since at least 1900, but how far north its native range reaches is unsettled, and BMIG does not say whether it is native here.
How big does Armadillidium nasatum get?
About 12 mm in the published figures. Sellers most often give 14 or 15 mm, and our care panels give 12 to 16 mm, a Dutch seller's figure.
Does Armadillidium nasatum need a heat mat?
Not in most heated homes: an English home averages about 19°C over the heating season, inside its 18 to 24°C band. For young through a cold winter, add a low-wattage mat on a thermostat, on the side of the tub and never underneath.
Are Armadillidium nasatum good for beginners?
Yes. Hardy, and happy with most of its floor dry, it forgives most mistakes except a wet, airless box.
Is Peach nasatum the same as Orange?
Most sources treat them as one colour under two names, though we found no published cross between the two.
Buying Nasatum
We keep four lines, and stock comes and goes, so check each listing: nasatum White, nasatum Orange, nasatum Dalmatian and the wild-type nasatum. Every nasatum we send is captive-bred, parcels go out from Monday to Thursday, and our live arrival guarantee covers every livestock order. For other species in the genus, see caring for Armadillidium isopods.
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