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Gestro's Pillbug (A. gestroi)
Armadillidium gestroi
The Giant Woodlouse of Gestro (Armadillidium gestroi). One of the largest European 'rolling' isopods, reaching up to 2.5 cm. A spectacular species featuring large mustard-yellow spots on a dark grey carapace.
Class:Malacostraca
Order:Isopoda
Family:Armadillidiidae
Genus:Armadillidium
Species:Armadillidium gestroi
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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: Endemic to the sunny limestone crevices and dry stone walls of the northwestern Mediterranean coast (southern France, Liguria, and north-tyrrhenian Italy).
Taxonomy and Genetics: Family Armadillidiidae. Named in honor of the Italian entomologist Raffaello Gestro. Distinguished from the common *A. vulgare* by its much larger size and finely granulated, rough carapace surface.
Behavior and Habits: Slow, docile, and nocturnal. Due to their large size, they are clumsy climbers and prefer to remain under heavy cork bark hides. They roll into tight, impenetrable spheres when threatened. Growth is slow, taking up to 1.5 years to reach maturity.
Morphology: Broad, high-domed carapace reaching up to 2.5 cm in length. The surface is matte and granulated. The background color is dark slate-grey to charcoal, adorned with symmetrical rows of bright mustard-yellow spots. Females are typically larger.
Care, breeding and tankmates
Terrarium Setup: Requires a spacious, well-ventilated enclosure. Provide a deep substrate (6-8 cm) of calcium-rich organic soil mixed with leaf litter, as they burrow to molt. Include multiple thick layers of cork bark.
Lighting and Heating: Do not expose to direct light. Maintain temperatures between 22-26°C. They become inactive and stop feeding if temperatures drop below 19°C.
Humidity and Hydration: Requires a distinct moisture gradient (50-75% overall). One side of the enclosure must be kept dry with dry leaf litter, while the other side is kept damp (using moist sphagnum moss) to allow respiration. Constant wetness will cause mortality.
Feeding and Supplementation: Primary decomposers. Feed on decaying hardwood leaves (oak, beech) and rotten wood. Provide a constant source of calcium (cuttlebone) to support the development of their thick, calcified carapace.
Compatibility: Peaceful decomposers. Avoid keeping them with large predators or damp amphibians that might consume them. Best kept in a dedicated culture or with other peaceful invertebrates.
Health and Common Diseases: Calcium deficiency can lead to failed molts (Rubber Shell disease), where the new carapace fails to harden, leading to death. Ensure a constant supply of calcium and dry oak leaves.
Geographic Origin and Distribution
Endemic to the sunny limestone crevices and dry stone walls of the northwestern Mediterranean coast (southern France, Liguria, and north-tyrrhenian Italy).
Origin
Europe, Mediterranean, and West Asia
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 Montesanto et al. — Armadillidium gestroi specimen measurements source reports a maximum adult measurement of 2 cm for this species, recorded as body length. The taxonomic record consulted is Armadillidium gestroi. 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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