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Milkback swift woodlouse
Porcellio laevis "Milkback"
A popular, striking two-toned color morph of Porcellio laevis, featuring a dark grey body with a broad, milky-white stripe down its back.
Class:Malacostraca
Order:Isopoda
Family:Porcellionidae
Genus:Porcellio
Species:Porcellio laevis "Milkback"
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Environment
Terrestrial
Humidity
50 - 70 %
Day temperature
20 - 26 °C
Night temperature
18 - 22 °C
UVB
None
Species description
Geographical Origin and Habitat: Porcellio laevis "Milkback" is a stable captive-bred color morph of the cosmopolitan isopod Porcellio laevis. The wild ancestor originates from Europe and the Mediterranean basin. In nature, the species inhabits moist, organic-rich microhabitats under rotting wood, leaf litter, rocks, and in compost. The "Milkback" morph was isolated and selectively bred by hobbyists to preserve its unique bicolored pattern.
Taxonomy and Genetics: Belonging to the class Malacostraca, order Isopoda, family Porcellionidae, and genus Porcellio. The "Milkback" mutation is recessive, affecting melanin distribution. It restricts dark grey pigmentation to the sides of the carapace while leaving a wide longitudinal band down the center of the back clean white. This genetic trait is highly stable.
Behavior and Habits: Like all Porcellio laevis, this morph is highly active, fast, and prolific. It is mostly nocturnal, but will display daytime activity in established, densely populated colonies. They aggregate socially under hides to conserve moisture. As efficient detritivores, they play an active role in decomposing decaying plant matter and recycling nutrients.
Morphology: Features a flattened, oval body reaching 2.0 to 2.5 cm in length as adults, with a smooth, glossy carapace. The distinguishing feature is the two-tone color pattern: a broad, creamy-white longitudinal stripe runs down the center of the dorsum (resembling spilled milk), while the lateral margins and the head are dark slate grey. Eyes and antennae remain dark.
Care, breeding and tankmates
Terrarium Setup: Can be easily housed in plastic tubs or glass tanks of at least 30x20x20 cm. The substrate should be 5-8 cm deep, consisting of coconut coir, peat moss, crushed rotten wood, and plenty of decaying hardwood leaves (oak, beech). Cork bark flats should be placed on the surface to provide cover and a cuttlebone for calcium.
Lighting and Heating: No specialized lighting is needed; ambient, indirect room light is sufficient. The ideal temperature range is 20°C to 26°C (68-79°F). Protect the enclosure from direct sunlight. Standard home temperatures are perfect, and no supplemental heating is required under normal conditions.
Humidity and Hydration: Establishing a moisture gradient is crucial. Dampen one side of the substrate with sphagnum moss to maintain 70-80% humidity, while leaving the other side dry with dry leaf litter. This allows the isopods to breathe through their pleopodal lungs without drying out or drowning in soggy soil.
Feeding and Supplementation: A varied detritivorous diet is required. Decaying wood and leaves are the staple. Supplement 2-3 times a week with fresh vegetables (carrots, squash), fish flakes, or dry pet food for protein. Keep cuttlebone or crushed eggshells available at all times to supply the calcium needed for shedding.
Compatibility: Can be kept with other Porcellio laevis morphs, but they will cross-breed, resulting in wild-type grey offspring. Excellent clean-up crew (CUC) in bioactive terrariums housing larger, non-insectivorous reptiles and amphibians. Avoid placing with tiny, delicate species that could be stressed by their activity.
Health and Common Diseases: Desiccation is the primary threat; a completely dry enclosure will crash the colony quickly. Poor ventilation causes stagnant conditions and toxic mold growth. Remove uneaten fresh food within 24-48 hours to prevent outbreaks of pest mites or fungus gnats.
Geographic Origin and Distribution
Porcellio laevis "Milkback" is a stable captive-bred color morph of the cosmopolitan isopod Porcellio laevis. The wild ancestor originates from Europe and the Mediterranean basin. In nature, the species inhabits moist, organic-rich microhabitats under rotting wood, leaf litter, rocks, and in compost. The "Milkback" morph was isolated and selectively bred by hobbyists to preserve its unique bicolored pattern.
Origin
Selective breeding and cultivarsEurope, Mediterranean, and West AsiaCosmopolitan or introduced
Terrestrial invertebrate profile
- Diet
- No verified data available
- Life expectancy
- No verified data available
- Adult size
- 2 cm
- Lifestyle/Microhabitat
- No verified data available
- Activity cycle
- No verified data available
- Sociality
- No verified data available
- Reproduction
- No verified data available
- Venom level
- No verified data available
- Handling tolerance
- No verified data available
- Brumation
- No verified data available
- Molting
- No verified data available
The catalog's scalar value is 2 cm. The British Myriapod and Isopod Group — Porcellio laevis source reports a maximum adult measurement of 2 cm for this species, recorded as body length. The biological datum refers to the base species Porcellio laevis, not exclusively to the commercial variety. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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