Cubaris sp. 'Rubber Ducky'

Cubaris sp. 'Rubber Ducky' is a terrestrial isopod (order Isopoda, suborder Oniscidea, class Malacostraca) — a crustacean, not an insect. The species has not been formally described yet, so it goes by a hobbyist trade name rather than a proper binomial. It was first collected from limestone cave environments in Thailand, where it lives in humid, calcium-rich microhabitats among karst rock formations.

The common name comes from the colour: a pale creamy yellow body with a slightly darker head and a smooth, rounded profile. They look a bit like rubber ducks. They are small to medium isopods, reaching about 1.5–2 cm as adults, with a convex, segmented body and the typical seven pairs of walking legs. They cannot conglobate as tightly as Armadillidium, but they do curl partially when stressed. Their behaviour is quite shy — they spend a lot of time tucked into crevices and under cork bark, and are most active at night or in dim conditions.

Rubber Duckies are popular because of the colour and because they have a reputation as a "collector's species." They breed slowly, they are less tolerant of husbandry mistakes than Porcellio or Armadillidium, and prices reflect that. This is not a beginner isopod. If you have kept a few Porcellio colonies successfully and understand moisture gradients, ventilation, and calcium supplementation, you should be fine. Lifespan is around 3–5 years with proper care.

Rubber Duckies need more precise conditions than hardy species like P. scaber or A. vulgare. The margin for error is narrower, mostly around humidity and temperature stability. Get those right and they do well. Get them wrong and the colony stalls or crashes.

Enclosure: A sealed or near-sealed plastic tub with controlled ventilation. Unlike Porcellio, which likes plenty of airflow, Cubaris species need high humidity retention. A small number of ventilation holes (not a fully mesh lid) is the way to go — enough to prevent completely stagnant air, but not so much that the enclosure dries out within a day. A 20×15 cm tub is adequate for a small starter group, but don't crowd them. These are slow breeders so you won't outgrow the space quickly.

Substrate recipe:

• 50% organic topsoil (no added fertiliser)
• 20% sphagnum moss (mixed in, not just on top)
• 15% coco coir
• 10% crushed limestone or oyster shell
• 5% orchid bark or small hardwood chips

The limestone is non-negotiable. These animals come from karst habitats and need constant access to calcium. Mix it into the substrate as well as providing a piece of cuttlebone on the surface. Depth of 5–8 cm. Top with dried oak or beech leaf litter and provide cork bark hides — they use the crevices between bark and substrate as their main shelter.

Temperature: 22–26°C. This is a tropical species and it does not tolerate cold well. Below about 18°C, activity and breeding stop. If your room drops below 20°C in winter, you will need a heat mat on a thermostat placed on the side or underneath the enclosure. Avoid heating from above — it dries the air inside the tub too quickly.

Humidity: 75–90%. High and consistent. Mist with dechlorinated water regularly — how often depends on your ventilation setup and ambient room humidity, but every day or two is typical. Even with high overall humidity, you still want a slight gradient: one side very damp, the other just moist rather than wet. Standing water or a fully saturated substrate causes problems. If you see pooling, you have gone too far.

Ventilation: Less than you would give Porcellio. A few small holes rather than a mesh lid. The goal is minimal but present airflow. If you see mould spreading aggressively across the substrate, increase ventilation slightly. A small amount of white mould is normal in a humid isopod enclosure and is usually harmless.

Diet: Dried leaf litter (oak, beech) as a constant food source. They eat slowly and won't chew through leaves as fast as Porcellio laevis does. Supplement with vegetables: cucumber, courgette, sweet potato. Cuttlebone or crushed eggshell for calcium — always available, not optional. Protein once a week in small amounts: dried shrimp, fish flakes, or a pinch of brewer's yeast. Remove any uneaten fresh food within 48 hours.

Social needs: Keep in groups. A minimum of 6–8, but more is better. They are not aggressive and do fine in close quarters. Don't mix with other isopod species — Cubaris are slow and will lose the competition for food and space against faster-breeding species.

Breeding: Slow. Females carry eggs in a marsupium and produce small broods — often just 10–20 mancae at a time. Brood intervals are longer than Porcellio, typically every 8–12 weeks in warm, stable conditions. Colony growth is gradual. Don't expect rapid expansion. It can take a year or more for a small starter group to become a visibly thriving colony. This is normal for the species.

Watch out for: Desiccation. This is the number one killer. If humidity drops or the substrate dries out, they dehydrate quickly — they breathe through gill-like pleopods and cannot survive dry conditions the way A. vulgare can. Temperature crashes in winter. Grain mites from overfeeding protein. And impatience — slow growth does not mean a failing colony. Give them time.

For general isopod care principles, see our isopod care guide.

Rubber Duckies need more careful packing than hardier species. They are shipped in a small ventilated deli cup with damp sphagnum moss packed snugly around cork bark pieces, giving the isopods plenty of crevices to shelter in during transit. The cup is placed inside an insulated postal box with a heat pack (winter) or cool pack (summer) to stabilise the temperature. We double-insulate during cold months because this species does not tolerate chilling the way temperate isopods do.

Shipping is Monday to Wednesday only, via Royal Mail Tracked 24, to make sure parcels are not left in depots over weekends. We are cautious with this species — if the forecast is below 4°C or above 27°C, we will hold the order and contact you to arrange a safer date. Losing a Rubber Ducky colony to transit stress is something we take steps to avoid.

When your isopods arrive: Open the deli cup in a warm, quiet room (22°C or above). Gently transfer the moss and bark — isopods and all — directly into their prepared enclosure. Do not pick individuals out by hand; they are small, easily injured, and will be stressed from transit. Mist the enclosure lightly and leave them undisturbed for at least 48 hours. They will likely hide immediately and may not be visible for several days. This is normal behaviour for Cubaris. Resist the urge to dig around looking for them.

All live orders are covered by our live arrival guarantee.