Armadillidium depressum Isopods (Southern Pill Woodlouse)

Almost everything in this hobby is an import from somewhere warmer, which is what makes the Southern Pill Woodlouse a quiet novelty: you could find one on a local wall. Armadillidium depressum is a native British isopod, common on old stone and brick across the south and west and spreading steadily north, and keeping a colony is a chance to work with a species from here rather than a Mediterranean or tropical one. It is a substantial, dark grey-to-black pill woodlouse with a distinctive flattened, splayed profile, and it makes both a characterful display animal and a hardworking clean-up crew.

The "depressum" in the name refers to that flattened shape. Where the common A. vulgare is high-domed and rolls into a perfect sphere, depressum is noticeably wider and lower, with the rear segments splaying outward, a body built for wedging into narrow cracks in walls and rock. That shape brings one behaviour worth knowing: it only partly conglobates, rolling into a ball that leaves a small gap between head and tail rather than sealing completely. It is normal for the species, not a fault, and a reliable way to tell it apart from vulgare. Its selectively-paled 'Magic Potion' morph shows the same trait.

Two things set it apart in the tub. It is an unusually confident isopod, inclined to keep foraging in the open when you lift the lid rather than bolting for cover, which combined with its size makes it well worth watching. And it is a real climber: in the wild it lives on vertical stone, so give it cork bark leaned against the walls and it will use the height, making for a more three-dimensional enclosure than a flat tub of substrate. For keepers who want to actually see their isopods at work, that is a real draw.

Care is easy and suits UK homes almost by definition. Keep a moderate humidity with a gradient, around 50 to 70%, one lightly damp corner under sphagnum with the rest allowed to dry between waterings, and medium ventilation, more airflow than a tropical species needs but less than the dry Spanish Porcellio. As a native it is happy at normal room temperature the year round, roughly 17 to 26°C, with no heating and no seasonal fuss. Skip a standing water dish, which only invites mould; they drink from damp substrate.

For substrate, mirror the limestone-wall habitat with a free-draining, calcium-rich mix: a base of flake soil, rotted hardwood and organic topsoil around four to six centimetres deep, sphagnum kept to the damp corner rather than mixed throughout, and crushed limestone or oyster shell distributed through for calcium, which this wall-dwelling species particularly appreciates. Cap it with magnolia and oak leaf litter and, importantly, some vertical cork bark for the climbing. A coco-coir-only base does nothing for them, so leave it out.

Feeding is the usual unfussy detritivore routine: leaf litter and rotting wood as the constant base, soft veg such as courgette, carrot and squash a couple of times a week with leftovers lifted promptly, and a little protein now and then, remembering that Armadillidium need far less of it than Porcellio do. Breeding is steady and year-round in stable conditions, with broods of roughly fifteen to thirty released as live miniatures, and colonies stay peaceable even at density. Compare it with the bright Spanish granulatum, pair it with a springtail culture to handle mould, or see the rest of the Armadillidium collection. Every order is captive-bred, boxed double-walled around a ventilated tub of damp sphagnum and posted Monday to Thursday by tracked next-day Royal Mail with a live-arrival guarantee and a 20% overcount as standard.