Armadillidium gestroi - "Gestroi"
ARMADILLIDIUM
Armadilidium gestroi originate from northwestern Italy. They are popular additions to terrariums and kept as pets for their striking visual appearance and relatively easy care. They make for a decent beginner species although they have a longer establishment phase and slow growth rate.
Species Characteristics:
Morphology:
Size - Large, 1.5 - 2 cm long as adults.
Gestroi demonstrate aposematic colouration with rows of bright-yellow spots contrasting against the rest of their body’s black to dark brown colour. Many individuals also have a pale grey “skirt” colour which wraps around the lateral margins of the body.
Gestroi belong to the genus Armadillidium, which is known for its ability to conglobate, meaning to roll into a tight defensive ball when startled, protecting the head and underside of their body.
Activity Level:
Low to medium.
Gestroi are slow moving isopods commonly seen underneath sticks and bark throughout the setup. They tend to remain above the substrate although mancae (babies) and smaller juveniles can occasionally be seen burrowing. They can be seen more active at night.
Reproductive Rate and Maturity:
Gestroi are slow to establish, generally taking around 3 months to begin reproducing once they enter a new setup. However, once they get comfortable and begin breeding, they can quickly become plentiful under correct care.
Gestroi take 6 - 12 months to reach sexual maturity and can have large clutch sizes, capable of producing roughly 30 - 100 mancae (babies) per clutch. The gestation period before the mancae may be around 2 months. During this time, they develop in the mother's marsupium, a temporary water-filled pouch on the underside of the mother's thorax, before being born.
Most isopod species are capable of reproducing once they hit 50% - 75% of their adult size. Additionally, clutch size generally correlates with the size of the gravid (pregnant) female, meaning the larger the female, the larger the potential clutch size.
Diet:
An isopod’s main diet is the leaf litter and substrate in their setup but it is recommended to supplementally feed your colony once or twice a week to ensure they get additional nutrition.
Gestroi enjoy protein alongside vegetables. Fish food and dried shrimp are popular protein sources. It is also observed that an abundance of protein boosts reproductive rates, useful when establishing a new colony.
Always be mindful and ensure no pesticides were used before feeding fruits and vegetables and remove any uneaten food after 1 - 2 days to prevent the onset of mold.
General Setup:
Enclosure Size:
Our recommended enclosure size for starting a colony of 12 - 24 isopods is a transparent 5 litre bin with three or four cross-ventilation holes along the length, each hole measuring roughly ½ mm.
Substrate:
Provide 2 - 3 inches of substrate that consists of a 60% vermicompost to 40% coco peat ratio. Substrate should be refreshed once or twice a year to prevent harmful frass (waste) buildup and maintain overall colony health.
Humidity, Hydration, and Temperature:
Adequate humidity is essential for all isopod species as they rely on respiration through pleopodal lungs on the underside of their abdomen which must stay moist to function. The best way for isopods to regulate their humidity requirements is through a moisture gradient.
Gestroi enjoy a moderate-to-high moisture gradient, meaning roughly 50% - 70% of the enclosure should be moist. Additionally, never allow the substrate to become bone-dry, even on the drier side of the setup.
Around ¼ - ⅓ of the enclosure should contain sphagnum moss which helps hold humidity. The dampest point of the setup should be on the far side of the enclosure under the moss.
Maintain these parameters by gently pouring and/or spraying water once a week or whenever the setup begins to dry out.
Note that gestroi can be susceptible to losses during heatwaves in the summer. They enjoy somewhat cooler conditions than some other species (20 - 26° ideally) but should do fine in your household environment.
Leaflitter, and Hides:
As dried leaf litter serves as one of their main food sources, it is important that your isopods always have a plentiful layer covering around 80% of the enclosure. We provide dried leaves from mango and almond trees but as a general rule, any leaves from hardwood trees are safe for isopods. Periodically replenish as needed.
Gestroi enjoy hiding among sticks and pieces of bark but can also be found under the moss on the moist side of the setup.
Calcium:
All isopods need a calcium source to maintain their exoskeleton and prevent issues when moulting. Common sources of calcium are cuttlefish bone and egg shell refined into small pieces. A calcium source should be scattered around the enclosure at the time of setting up and periodically refreshed when needed.
