Porcellio Werneri Silverback Isopods (Greek Shield Isopod)

A Glimpse

• Scientific Name: Porcellio werneri "Silverback"
• Common Names: Greek Shield Isopod, Pancake Isopod, Werner's Woodlouse
• Family: Porcellionidae
• Origin: Greece — rocky, dry habitats on the Aegean islands and surrounding areas
• Adult Size: Up to 20 mm
• Difficulty: Medium — not a beginner species, but manageable if you understand what they need
• Temperature: 17–26°C (room temperature is fine)
• Humidity: 50–65% — this is a dry-habitat species
• Ventilation: Medium to high — good airflow is important
• Diet: Leaf litter, rotting white wood, vegetables, protein supplements, moss, lichen
• Supplements: Cuttlebone, crushed limestone, or oyster shell — calcium is important
• Breeding: Seasonal — only 1–2 broods per year

What Makes Werneri Special

Porcellio werneri is one of the most visually distinctive isopods you can keep. Forget the usual rounded woodlouse shape — these are flat. Remarkably flat. The body is broad, disc-like, and shield-shaped, with a wide white or cream skirt edging the dark central body. They look like tiny flying saucers, or — as the common name suggests — miniature Greek shields.

The "Silverback" variety adds to this with a prominent silvery-white stripe running down the centre of the back, creating even more contrast against the dark body. It's a naturally occurring variation from a distinct wild population, not a selectively bred morph, which gives it a slightly different character to the standard grey P. werneri.

The flat body shape isn't just aesthetic — it's a functional adaptation. In their native Greece, these isopods inhabit rocky, dry limestone habitats where being able to press flat into crevices and under stones is a survival advantage. In captivity, you'll see them doing exactly the same thing — gripping flat against cork bark, wedged into narrow gaps, or pressed against the sides of hides. It's a very different behaviour from rounder isopod species and it's fascinating to watch.

Enclosure

A standard culture tub (12 litre) is sufficient for a starter colony, but P. werneri benefits from more space than many isopod species for an important reason: adult males can be territorial. They may squabble with other males, and in a cramped enclosure this can become a problem. A 25 litre tub gives a more established colony room to spread out and reduces conflict.

Provide plenty of hides — cork bark pieces (both flat and curved), stone pieces, and stacked structures work well. The flat body shape means these isopods will use very narrow gaps that other species can't fit into, so thin crevices between cork bark pieces or flat stones are particularly appreciated.

Consider arranging hides at different heights. Using a taller enclosure with stacked or raised structures gives the isopods the ability to self-regulate their position relative to the moisture gradient — closer to the damp substrate when they need moisture, higher up in drier air when they don't.

Substrate and Humidity

This is where P. werneri differs significantly from most isopods you might have kept. They're a dry-habitat species. The natural habitat is rocky, calcareous limestone terrain in Greece — not tropical forest floor.

In practical terms, this means keeping the enclosure drier than you would for most other species. No more than a third of the substrate should be damp at any time. A patch of moist sphagnum moss in one corner provides a hydration zone they can visit when needed, but the majority of the enclosure should be dry to moderately dry.

The substrate itself should be organic topsoil with leaf litter and crumbled white rotten wood. Keep it on the drier side overall. The moisture gradient is critical — damp at the bottom, dry on the surface, with a distinct wet patch in one area and the rest left dry.

Good ventilation supports this. Airflow helps prevent the enclosure from becoming too humid and reduces the risk of mould, which thrives in the stagnant, damp conditions that would stress this species. Mesh vents in the lid or upper sides of the enclosure are the simplest way to achieve this.

An important note: dry doesn't mean bone dry. All isopods need access to moisture for respiration and moulting. The goal is a predominantly dry enclosure with reliable access to a small damp area — not a desert. Getting this balance right is the main skill involved in keeping P. werneri.

Temperature

17–26°C — which, for most UK houses, is simply room temperature. No additional heating or lighting is needed in the majority of situations. Avoid placing the enclosure in direct sunlight or near radiators, which can dry things out too aggressively and cause temperature spikes.

These isopods are comfortable across a fairly wide temperature range, which is one of the things that makes them more manageable than their reputation might suggest.

Diet

The primary diet is leaf litter and decaying white rotten wood, both of which should always be available in the enclosure. Interestingly, P. werneri reportedly prefers more aged, well-decayed leaves over fresher ones — so don't worry about replacing leaf litter the moment it starts breaking down. That's when they want it most.

Supplement with root vegetables (sweet potato, carrot, yam) and other veg. Protein is important — offer fish flakes, dried shrimp, or freeze-dried bloodworm once or twice a week. Calcium should always be available: cuttlebone is the simplest option.

Remove uneaten fresh food before it moulds. In a drier enclosure this is slightly less urgent than with tropical species, but still good practice.

Breeding

Here's the thing that sets P. werneri apart from most Porcellio species you might be used to: they're seasonal breeders. While most Porcellio will breed continuously if conditions are right, werneri typically only produce 1–2 broods per year. This is a significant difference and it means colony growth is slow.

This isn't a fault in your husbandry — it's the natural reproductive strategy of the species. In their native Greek habitat, they've adapted to breed in response to seasonal cues rather than breeding constantly. In captivity, you can't really override this with warm temperatures or extra food. They breed on their own schedule.

The practical implication is that starting with 5 is fine, but you shouldn't expect the rapid colony expansion you'd get from something like P. scaber or P. laevis. Building a large colony takes time — potentially years rather than months. This is part of why they remain rare and relatively expensive despite being well-established in the hobby.

Male Territoriality

Worth mentioning separately because it's unusual for isopods: adult male P. werneri can be territorial and may fight with other males. This is rarely a serious problem in a well-sized enclosure with plenty of hides, but it's something to be aware of. Providing enough structure and space for males to establish their own areas reduces conflict. In a small, bare container with too many adult males, you may see aggression.

Being Realistic

At £40 for 5, P. werneri Silverback sits at a mid-range price point. The difficulty rating of Medium is fair for captive bred stock — these aren't as demanding as Ardentiella or challenging Cubaris species, but they do require you to understand and manage a dry setup, which is the opposite of what most isopod care guides teach.

If you've only kept tropical or temperate species that like it damp, the adjustment to a dry-habitat species is the main learning curve. The instinct to mist regularly and keep things humid will work against you with werneri. If you can resist that instinct and trust the moisture gradient approach, they're perfectly manageable.

The slow breeding is the other factor to consider. If you want a colony that fills out quickly and gives you the satisfaction of rapid growth, this isn't the species for that. If you're happy with a slower-paced, more deliberate keeping experience where each new brood feels like an event, werneri is genuinely rewarding.