Giant Orange isopods are Porcellio laevis 'Orange', an orange colour form of the swift woodlouse, or smooth slater, and the same species as the Dairy Cow and the Snow White. Our care panel gives an adult length of up to 20 mm, 20 to 26°C and 50 to 70% humidity, and rates them very easy. The one thing to get right is protein: this is a hungrier woodlouse than most, and a colony kept short of it can start nibbling its own soft, freshly moulted members. Give them 5 to 8 cm of flake soil, white-rotted hardwood and organic topsoil under leaf litter, a damp end and a drier end with air moving over both, and calcium in the tub at all times. Our Giant Orange isopods are captive-bred.
What the Giant Orange Is
Latreille named Porcellio laevis in 1804. The wild animal is grey to brownish-grey, with a glossy back that lacks the pebbled texture of the common rough woodlouse, Porcellio scaber: laevis means smooth, and "swift" is for the way it runs. The Giant Orange is one of several colour forms kept in the hobby, alongside the piebald Dairy Cow, the near-white Snow White, the Milk Back and the wild-type Grey, all one species with one set of care figures.
Our panel gives its origin as North Africa and the Mediterranean; it now lives worldwide, mostly near people. In Britain it is a scarce and declining resident. Sub-fossil remains from a medieval pit at Stonar, East Kent, put it here by the late thirteenth century, and through the twentieth century it turned up mainly in stables, cattle yards and dung heaps (Harding, 2016). The 2024 update to the national woodlouse atlas counts just seven records since 2008, all in south-east England, and none from Ireland; in 2023 the orange form itself was photographed in an East Sussex garden (Gregory, 2024).
Why "Giant"?
Not for its size within the species. Our panel gives 20 mm for every P. laevis colour form, the published maximum, and we have found nothing to suggest the orange grows larger. According to one US breeder's account from 2020, "giant orange" was first used about fifteen years earlier for an orange line of Porcellio scaber that was no bigger than any other P. scaber, and European sellers later carried the name over to orange laevis. Against other orange woodlice the name fits: P. scaber grows to 17 mm and Porcellionides pruinosus, the species sold as Powder Orange, to 12 mm.
Nor is it the giant Spanish orange. Porcellio expansus 'Orange' is a different species from north-east Spain; the largest male Vandel measured, in 1951, had a 28 mm body and reached 40 mm with its uropods. It breeds slowly, wants a drier tub and is no first isopod; our Porcellio expansus care guide covers it.
Appearance and Colour
Expect a broad, flat, glossy woodlouse that cannot roll into a ball and runs instead. The orange ranges from peach and apricot to a deep, bright orange, often with a paler rim around the body and pale flecks across the back, and the eyes are dark. Some adults show darker shading down the middle of the back. Males carry long, spear-shaped uropods at the tail end, the easiest way to sex them.
Young animals can look much paler, as in the group below.
How the Colour Is Inherited
We have found nothing published on the genetics of the orange form or on who first picked it out; the same US breeder's account says only that it was isolated in Europe between about 2015 and 2020. Hobby sources describe it, like the Snow White, as recessive. On that account two orange parents give orange young, while a cross to a Grey gives grey young that carry orange unseen, and orange returns when two of those are paired. Mixed with a Dairy Cow or a Snow White, the colours can be hidden or muddied, so keep each colour form in its own tub. Our guide to isopod genetics, colours and morphs explains how recessive lines behave.
Setting Up the Tub
A clip-lock tub with a tight lid suits them, since mancae find any gap. A starter group settles in 3 to 10 litres; my own standard is 11 litres, since the extra substrate and moss hold humidity and warmth more steadily. I use two to four large vents per tub. Put them on opposite sides so air passes through instead of stalling, and lay cork bark across the surface.
Lay 5 to 8 cm of flake soil, crumbled white-rotted hardwood and organic topsoil, deep enough for the females to dig the hollows they brood in, under a thick layer of dead hardwood leaves. Leave coco coir out of the mix: it holds moisture but is not food, and these woodlice eat the floor they live on. Calcium stays in at all times: a cuttlebone, pieces of limestone or both. Every one of my isopod colonies has tropical white springtails in with it, grazing the soft mould around the food.
Temperature and Humidity
Our care panel gives 20 to 26°C. An English home averages about 19.0°C through the heating season, October to April, and 18.1°C in December, both below the band, while July and August average about 21.5°C, at its lower end. They tolerate a cooler room, though they breed better with some additional heat from autumn to spring: a heat mat or heat cable on a thermostat, fixed to the side of the tub at one end and never underneath. Aim for 20 to 26°C, not 28°C and above; for mats, cable and thermostats, see our guide to heating isopods.
The studies point to a temperate animal. Animals kept at an average of 24°C righted themselves as well at 15°C as at 25°C (Bozinovic and colleagues, 2016); work on Chilean populations put their performance optimum at 20.9 to 24.7°C, a measure of performance rather than of a preferred temperature (Castañeda and colleagues, 2004, Evolutionary Ecology Research 6); and a laboratory colony bred at a constant 20°C (Ghemari and colleagues, 2017).
Humidity on our panel is 50 to 70%, and that range covers the whole tub: about 50% at the drier end and about 70% at the damp end, under a pad of moss. Mist the damp end, not the whole tub. Stagnant, humid air kills isopods that need airflow, which we know from keeping them rather than from a study, so the vents matter as much as the misting. Condensation on the lid, or substrate that turns to mud or smells sour, means it is too wet.
Feeding
Leaf litter and rotting hardwood are the base of the diet and should never run out. Add vegetables such as courgette, squash, carrot or sweet potato a couple of times a week, and lift anything uneaten within a day, before it moulds. Keep a little protein in the tub all the time, such as fish flakes, dried shrimp or a dried insect food, as our Dairy Cow guide advises for this species. A well-fed colony is no trouble. An underfed one goes looking for protein wherever it can find it: its own freshly moulted members, small or soft-bodied tankmates, and in a vivarium the skin of a sleeping reptile.
Breeding
Both sexes are needed. The female carries her fertilised eggs in a fluid-filled brood pouch under her body, the marsupium, and the young, called mancae, leave it small and pale. In Tunisian melon fields, wild females of 5.4 to 13.2 mm carried between 4 and 117 eggs, averaging about 32 to 79 depending on season and site, and the bigger the female, the more eggs (Amari and colleagues, 2019). Adults can reach 20 mm, well beyond the largest female in that study, and the keeper's figure in our Dairy Cow guide is 50 to 100 mancae a brood from established females.
At a constant 20°C, females kept under 16 hours of light a day started breeding after about 50 days and managed up to four broods in a row, while those kept in constant darkness took 136 days and managed one (Ghemari and colleagues, 2017). Wild animals in the Tunisian study lived an estimated 17 to 22 months; most woodlice live about two years, some three or four.
I start colonies with twenty or more animals where I can. After that, the usual problem is too many rather than too few: once a tub is crowded, split it or pass some on. That surplus lets reptile and amphibian keepers use them as feeders, and in a vivarium a colony works as a cleanup crew. Keep them away from small, soft-bodied or delicate tankmates, where no amount of feeding makes them a good neighbour, and expect them to outcompete shy or slow isopods at feeding time.
Frequently Asked Questions
Are Giant Orange isopods the same as Dairy Cow isopods?
Yes. Both are Porcellio laevis, as are the Snow White, the Milk Back and the wild-type Grey. They differ only in colour and share the same care.
Why are they called Giant Orange isopods?
It is a trade name, not a size difference. One US breeder traces it to an orange Porcellio scaber line, and we have found no evidence that orange P. laevis outgrows a Grey or a Dairy Cow.
Are Giant Orange isopods Porcellio expansus?
No. The Giant Orange is Porcellio laevis. Porcellio expansus 'Orange' is a separate, much larger Spanish species that breeds slowly and is not a beginner's animal.
Do Giant Orange isopods need a heat mat?
Not to keep them alive. They tolerate a cooler room, though they breed better with some additional heat from autumn to spring, when an English home averages about 19°C. Use a heat mat or heat cable on a thermostat, fixed to the side of the tub, never underneath.
How fast do Giant Orange isopods breed?
Fast. In one laboratory study, females at 20°C under long days started breeding about 50 days into the trial, against 136 in constant darkness, and wild females have been found carrying up to 117 eggs.
Can Giant Orange isopods live with reptiles?
Yes, as a cleanup crew or feeder colony, provided they are kept well supplied with protein. Keep them away from small, soft-bodied or delicate animals such as thumbnail frogs.
Where to Go From Here
The Giant Orange is about as forgiving as isopods get. There is no single right way to keep any invert, but steady protein and calcium, air moving over a damp end and a drier end, and some warmth from autumn to spring cover most of what this one needs. Our Dairy Cow isopod care guide covers the species in more depth, common mistakes included.
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