Armadillidium scaberrimum 'Sandstone' Isopods

For years this animal moved through the hobby under the wrong name. Stock now sold as the Sandstone Isopod was traded as Armadillidium omblae, and it was never that species. The distinction is worth getting right, because this was not a renaming. Armadillidium omblae has not gone anywhere. It is a valid species with its own description, a different animal entirely, and it still carries that name today. What happened is that hobby stock was misidentified, and the misidentification has since been corrected. The animal on this page is Armadillidium scaberrimum, described by Stein in 1859.

The trade name is an honest description of the texture and a poor description of the colour. The carapace is rough all over, covered in low spiny lumps that catch the light and break up its outline, and that is where the sandstone idea comes from. The colour is not sandy at all. It runs pinkish-lilac through to a soft lilac-grey, and a freshly moulted individual often shows a bluish cast down the line of the spine before the pigment settles back. Anyone expecting a beige desert isopod will get something cooler in tone and better looking. Adults reach about 20mm, so the sculpting is visible across the tub without a lens.

Underneath the shell this is a straightforward Balkan pill woodlouse, native to Croatia and the wider Balkans, and unusually tolerant of a broad spread of conditions. It conglobates like every true pill woodlouse, closing into a ball when disturbed, and the lumpy finish stays on show around the outside of that ball. Activity runs through the day as much as the night and is not confined to darkness, so a settled group is one you actually see rather than one you keep on trust.

Warm room, dry floor

Temperature is the uncomplicated part. Anywhere from 17 to 26°C suits it, and the band is wide enough that the seasons look after themselves. Humidity is where keepers go wrong. Aim for 50 to 65 per cent, drier than most people expect from a pill woodlouse, and arrange it as a slope from damp to dry, never one flat reading. In practice I keep about a fifth of the floor area damp and let the remaining four fifths run dry. Medium ventilation goes with that, enough airflow that moisture leaves the enclosure instead of hanging in it.

Substrate and feeding

A nutritious base substrate 5 to 8cm deep is all this species needs. Cover it with a generous layer of dry hardwood leaf litter, which gives the colony shelter and something to graze at for weeks on end, and add bark for the group to gather under. There is always cuttlebone or crushed shell in my tubs, because clean moults depend on a constant supply. Vegetables go down readily and an occasional protein source keeps things ticking over.

Undemanding, robust and hard to upset, this is a sensible pill woodlouse for anyone stepping past their first species. It is prolific, though not in the way people picture: it produces large broods at intervals rather than a steady trickle of young, so numbers can sit still for weeks and then jump. Adults last two to three years. If the Adriatic angle appeals, the Clown comes off the same stretch of Croatian coast and is the bold-patterned opposite of this one, with Skeleton-Nebula a second line of that same species. For more texture, we also keep the spiny Beier's Pill Woodlouse, and Armadillidium granulatum is the pebbled Spaniard. Our Armadillidium care guide covers the genus, and the wider Armadillidium range shows what else sits on that shelf.

Sandstone go out over damp sphagnum, the deli tub vented, the outer box carrying two walls of card. Posting days run Monday to Thursday with nothing after that, next-day Royal Mail with tracking, before 1pm, so no group of ours spends a Saturday in a sorting office. Counts include spares beyond what you asked for, and the live-arrival guarantee applies as always.