Scarlet isopods (Ardentiella sp. "Scarlet," formerly Merulanella) are part of our Heirloom Collection. Vivid scarlet red with custard yellow and jet black accents, they are a close relative of the Ember Bee and share its bold, climbing personality. Care is the same as other Ardentiella: lots of airflow, a real dry zone, cool stable temperatures, and plenty of vertical structure.
Scarlet Isopod Quick Facts
- Scientific name: Ardentiella sp. "Scarlet" (formerly Merulanella sp.)
- Origin: Vietnam
- Adult size: Up to about 2 cm
- Care level: Intermediate to advanced
- Temperature: 66 to 79°F, favor the cooler end
- Humidity: Moderate, with a strong dry zone
- Ventilation: High
- Breeding rate: Moderate for a premium Ardentiella, slower than common species
- Maturity: Roughly 5 to 7 months
- Activity: Active, bold, climbing, often visible in the open
A Note on the Name
You will see these listed under two genus names. They were sold for years as Merulanella. In 2025, researchers Kästle and Regalado Fernández reassessed that group and described the new genus Ardentiella, named from the Latin for "burning" or "fiery" after the bold colors of its members. The Southeast Asian species in the hobby, including Ember Bee and Scarlet, are now sold as Ardentiella.
The Two Things That Matter Most
- High ventilation. Ardentiella need much more airflow than most tropical isopods. Vent two opposite sides so air actually crosses the enclosure. Stagnant, humid air is the most common reason colonies crash.
- Climbing structure. They climb rather than burrow. Build the enclosure around vertical cork bark, branches, and lichen covered sticks instead of deep substrate.
Enclosure Setup
Use a taller enclosure with cross ventilation and a tight fitting lid. Adults and especially young can climb smooth plastic and glass, so treat any gap as an exit.
A moderate layer of our ABG style mix (recipe here) holds moisture and supports microfauna. You do not need the deep substrate that burrowing Cubaris want. On top, add:
- A thick layer of hardwood leaf litter, topped up as it gets eaten
- Decaying hardwood
- Cuttlebone for calcium, available at all times
- A culture of Tropical Pink springtails to keep mold and leftovers in check
- Upright cork bark and branches
- Lichen covered sticks for climbing and grazing
Humidity and the Moisture Gradient
Keep them on the drier side compared to Cubaris, with a clear dry zone. Mist one side and keep damp sphagnum there, and let the other side stay distinctly drier. The substrate should be damp, never waterlogged. Moisture plus airflow, never moisture alone.
Temperature
Keep them on the cooler side, roughly 66 to 79°F, and favor the lower end. Heat is a bigger risk than cold for this genus. Do not use a heat mat, keep them out of direct sun, and plan a cooler spot for them if your home runs warm in summer.
Feeding
Leaf litter and decaying hardwood should always be available, and they also graze on lichen. Offer small amounts of fish flakes, freeze dried shrimp, or soft vegetables and remove leftovers within a day, since food molds quickly in a humid bin. Keep cuttlebone available at all times.
Breeding
Scarlets breed slower than common species, with small broods, and only once a group is settled. In our experience Ardentiella take roughly five to seven months to mature. If a colony stops producing, check airflow, temperature, and moisture before anything else. Young tend to hide deep in leaf litter at first, so do not worry if you see few juveniles early on.
Common Mistakes
- Not enough ventilation. The number one killer for this genus.
- Keeping them too wet. They want a real dry zone.
- Setting them up like a burrowing species. Give them vertical surfaces.
- Letting them get too warm. No heat mats, no hot rooms.
- A loose lid. Young climb smooth walls and find gaps.
Common Questions About Scarlet Isopods
Are Scarlet isopods Merulanella or Ardentiella?
Both names refer to the same animals. Scarlets were sold as Merulanella and are now placed in Ardentiella after a 2025 reassessment.
How are Scarlets different from Ember Bees?
They are close relatives with the same care. Scarlets are a deeper red with yellow and black accents, while Ember Bees fade from black into red, orange, and yellow.
Do Scarlet isopods climb?
Yes. Like all Ardentiella, they climb more than they burrow, so a tall enclosure with upright bark and a sealed lid is important.
Are Scarlets good for beginners?
They are intermediate to advanced and best for keepers with some experience.
Where to Buy Scarlet Isopods
All Scarlet Isopods at Creature Cache are captive bred and ship FedEx Priority Overnight with a 100% live arrival guarantee. Shop Scarlet Isopods, or join the Creature Club for restock alerts and 10% off your first order.
More reading: How to Set Up Your First Isopod Enclosure, our ABG substrate recipe, and our springtail care guide.
Questions about your animals? Email us anytime at info@creaturecache.com.