Two woodlice from different families are sold as Lava isopods, and we keep both. One is Porcellio scaber 'Lava', an orange-and-grey colour form of the common rough woodlouse: our care panel gives 17 to 26°C, 55 to 70% humidity and an adult length of 15 to 17 mm, and rates it very easy. The other is Ardentiella sp. 'Lava', an undescribed climber sold as Vietnamese, from the group the hobby used to call Merulanella: 20 to 23°C, 60 to 75% humidity and 18 to 20 mm on our panel, rated hard. Before anything else, check which one you are buying. The scaber wants a mostly dry, airy tub and forgives nearly anything; the Ardentiella needs humid air that keeps moving and a room that never runs hot. Our Porcellio scaber Lava isopods and Ardentiella Lava isopods are both captive-bred.
Two Animals, One Name
Porcellio scaber Latreille, 1804, a European woodlouse now found worldwide, belongs to the Porcellionidae, the flat, fast woodlice that cannot roll up. Ardentiella belongs to the Armadillidae, a family built to roll into a ball, though this genus seldom does. Being in different families, they cannot interbreed.
Side by side they are easy to tell apart. The scaber Lava is oval and flat, with a bumpy back mottled orange and grey and two short points at the tail. The Ardentiella Lava has a smoother back and a rounded rear with no tail points showing; in our listing photos they are slate-grey with red-orange along the lower edges of the segments, more on some animals than others, and the body is built for climbing and life on the surface rather than burrowing.
Where the Names Come From
On what we could find, the scaber name is the older. Hobby breeders were writing about scaber Lava lines as something already established in 2020, but we have found no account of who first bred it, or where. Breeders disagree on how the pattern is inherited, and we have found nothing published on it.
In March 2025 Kästle and Regalado Fernández split the old genus Merulanella, leaving three New Caledonian species in it and naming Ardentiella, from the Latin for burning or fiery, for two species from Myanmar. The colourful Vietnamese trade animals sit in it as undescribed species. The paper names no trade morph, so 'Lava' is a hobby label hung on the genus, and you will still see it sold as Merulanella 'Lava'.
Keeping Porcellio scaber 'Lava'
This is the woodlouse you turn up under a plant pot, in brighter colours. The British Myriapod and Isopod Group gives the species to 17 mm, with a rough, heavily tuberculate back (scaber is Latin for rough), and notes that it copes with drier places than the shiny woodlouse Oniscus asellus and readily climbs walls and trees. So keep a lid on, and keep the tub mostly dry with one damp end.
Temperature and Humidity
Our care panel gives 17 to 26°C. An English home averages about 19.0°C over the heating season, October to April, and about 21.5°C in July and August, so a heated room keeps the tub in the band for most of the year with no heat mat. A room that drops below 17°C in winter wants one, on a thermostat and fixed to the side of the tub, never underneath; our guide to heating isopods explains how to fit one.
Few woodlice have been measured as closely. Garden animals from Kraków, offered a choice of temperatures, settled at about 20.9°C (Antoł and colleagues, 2019). In a two-week laboratory test, P. scaber ate almost twice as much leaf at 28°C as at 20°C, but mortality was 2.5 times higher, 23.4% against 9.4% (Römbke and colleagues, 2011). Warmth also speeds development: young took 59.3 days to develop in the pouch at 15°C and 23.1 days at 22°C (Horváthová and colleagues, 2015). Aim for the low twenties and do not run it hot.
Our panel gives 55 to 70% humidity across the whole tub, the drier end at the low figure and the damp end at the high one: a third kept damp under moss and bark, the rest left to dry between light mistings.
Setup, Food and Breeding
Lay 5 to 8 cm of flake soil, white-rotted hardwood and organic topsoil under leaf litter, with cork bark for cover. Woodlice eat their substrate, and coco coir holds moisture but is not food, so leave it out. Leaf litter and rotting wood are the staple; offer vegetables such as carrot or courgette, and most keepers add a little protein, such as fish flake, once a week, with many Porcellio keepers going to twice. Keep calcium in at all times: a cuttlebone or pieces of limestone.
Both sexes are needed. The female carries her eggs in a brood pouch, the marsupium, and the young, called mancae, leave it small and pale with six pairs of legs; the seventh pair grows over the next few moults. A colony runs from all-orange animals through mottled ones to plain grey, and keeping the colour bright means breeding from the brightest. Most woodlice live about two years, some three or four.
Keeping Ardentiella sp. 'Lava'
With this one, the hard part is ventilation: it wants humid air and moving air at once, and most of what raises humidity also cuts the airflow. Stagnant, humid air kills Ardentiella; we know that from keeping them, not from a study.
Air, Temperature and Humidity
Cross-ventilate: fine mesh in one wall and more in the wall facing it, so air travels across the box instead of stalling behind a single vent. On my own tubs that means two to four large vents each, with oscillating fans keeping the air on the move. Our panel gives 60 to 75% humidity: damp at one end under moss and bark, near 75%, and drier at the far end, near 60%, never wet throughout.
Keep them cool. Our panel gives 20 to 23°C, the band they do best in, and they tolerate 19 to 26°C. An English home averages about 19.0°C over the heating season, the cool edge of that range; 18.1°C in December, just under it; and about 21.5°C in July and August, inside the best band. Keep them in a heated room with no heat mat. The hazard is a summer hot spell: keep the tub out of the sun and away from radiators, and move it somewhere cooler if the room nears 26°C. We have found no published temperature study of any Ardentiella, so these figures are house practice, not measurement; seller figures disagree by several degrees.
Climbing, Substrate and Food
The 2025 paper cites keepers' and collectors' observations of the genus on vegetation and other exposed surfaces, and says its members "only rarely use the ability to conglobate": they can roll, but seldom do. They climb smooth plastic and glass, mancae included, so the lid must close tight everywhere except the mesh. Height matters more than floor space: stand cork bark on edge, add branches, and leave a damp, mossy spot under bark for moulting.
On the floor, use 5 to 8 cm of the same soil and hardwood mix, moist but never waterlogged and damper at one end, topped with deep hardwood leaf litter and white rotten wood, which make up most of the diet. Offer small pieces of soft vegetable, and most keepers add a little protein once a week; lift fresh food after a day, since leftovers mould fast at this humidity. Lichen is worth offering; ours graze it, though nothing published says any woodlouse needs it. Keep calcium in permanently, and replace the substrate every six months, as our listing advises, before frass builds up. Tropical white springtails live in all my isopod colonies, and here they graze the soft mould you miss.
Breeding
Both sexes are needed, and the mancae colour up over successive moults, so do not judge a line by its young. Our listing calls the breeding rate fair to prolific once a colony settles, but also warns that a starter group can take a year or more to show real recruitment. We have found no published brood size or age at maturity for any trade Ardentiella. Keep 'Lava' in its own tub: we have found nothing published on which Ardentiella morphs can interbreed.
Which Lava Should You Choose?
For a first isopod, a cleanup crew or a hardy breeding project, choose the scaber: it takes a wide band of conditions and breeds steadily. Choose the Ardentiella if you have already kept a demanding isopod successfully, can hold a room cool in summer and want an animal you will see out on the bark. If you like the look but have not kept the genus, start with Ember Bee isopods, which want the same tub and the same air; our Ember Bee listing calls them the gentlest introduction to the group.
Frequently Asked Questions
Are lava isopods Porcellio scaber?
Some are. 'Lava' is used for a colour form of Porcellio scaber and for an unrelated Ardentiella sold as Vietnamese. Check the Latin name on the listing: the scaber is mottled orange and grey with a rough back, the Ardentiella smooth-backed and rounded at the rear, with no tail points showing.
How big do lava isopods get?
The scaber Lava reaches 15 to 17 mm on our panel, and the species is recorded to 17 mm. The Ardentiella Lava reaches 18 to 20 mm on our care panel; we have found no published measurement for it. The largest described Ardentiella, A. bicolorata, has a 13 mm maximum in the 2025 paper, but the trade animals are undescribed.
Do lava isopods need a heat mat?
The scaber needs one only if the room falls below 17°C in winter, on a thermostat and fixed to the side of the tub. The Ardentiella needs no heat mat: keep it in a heated room, out of the sun and below about 26°C.
Do lava isopods roll into a ball?
The scaber cannot; it runs or freezes. The Ardentiella belongs to a rolling family but, in the words of the 2025 paper, only rarely uses the ability.
Can lava isopods climb?
Both can. The scaber climbs walls and trees in the wild, and the Ardentiella climbs smooth plastic and glass, young included. Keep a secure lid on either.
Are lava isopods good for beginners?
The scaber Lava is one of the easiest isopods you can keep. The Ardentiella Lava is not a first isopod, or a first Ardentiella.
Where to Go From Here
Our Porcellio scaber care guide goes further into the species, and our Ardentiella care guide covers the whole genus. Build the tub and let it settle before you order.
Leave a comment