Polyrhachis murina

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Borneo and Sumatra in the Indomalaya region ^[1][2].
• Colony Type: Colony structure is unconfirmed. We do not know if they host single queens or multiple queens.
• Size & Growth:
  • Queen: Unknown, queens have not been measured or described
  • Worker: ~6.5-7.0 mm in total length ^[1]
  • Colony: Unknown, no colony size data exists in the literature
  • Growth: Unknown
  • Development: Unknown, no development data exists for this species (Related tropical Formicinae often take several months to produce workers, but exact timing is unconfirmed.)
• Antkeeping:
  • Temperature: Keep warm and stable, roughly 22-28°C. As a tropical species, they do not tolerate cold ^[2].
  • Humidity: High humidity required. Keep the nest substrate consistently moist but never waterlogged ^[2].
  • Diapause: Unknown, tropical range suggests they do not require winter cooling, but this is unconfirmed.
  • Nesting: They likely nest in rotting wood or under bark in the rainforest ^[2]. Use a Y-tong (AAC) nest or plaster formicarium that holds moisture well.
• Behavior: These ants are generally calm and moderately active. They lack a functional sting and instead defend themselves by biting and spraying concentrated formic acid from an acidopore ^[2]. Workers forage for sugar sources and small insects. They are medium-sized, so standard escape prevention like Fluon barriers is still necessary.
• Common Issues: humidity control is critical, tropical ants dry out quickly in low humidity, temperature drops can halt colony development, keep them warm year-round, escape prevention is still necessary despite their moderate size, slow colony growth can frustrate beginners, founding takes time, wild-caught colonies may carry parasites that can decimate captive colonies

Housing and Nest Setup

Set up a nest that holds moisture well but still allows airflow. A Y-tong (AAC) nest or a plaster formicarium works perfectly for this species ^[2]. Make sure the chambers are large enough for 6-7 mm workers to move around comfortably. Connect a water reservoir or moisture chamber to keep the substrate damp. You can start a new queen in a test tube, but move her to a larger nest once she has a few workers. Keep the outworld spacious so you can easily place food and water dishes.

Feeding and Diet

These ants likely feed on honeydew from aphids and scale insects, plus small arthropods they scavenge or hunt ^[2]. In captivity, offer a steady source of sugar like diluted honey water or syrup. Provide protein sources like small crickets, mealworms, or fruit flies two to three times a week. Remove uneaten prey within a day to stop mold from growing. New queens will not eat until their first workers hatch, so just keep the outworld clean.

Temperature and Seasonal Care

Keep your colony warm year-round. Aim for roughly 22-28°C ^[2]. Since they come from tropical rainforests, they do not experience cold winters and likely do not need a diapause period ^[2]. Use a heating cable on one side of the nest to create a gentle gradient. Watch how the workers react, if they cluster near the heat, raise the temperature slightly. If they stay deep in the nest and move slowly, the nest might be too warm.

Humidity Management

Maintain high humidity by keeping the nest substrate consistently moist but never waterlogged ^[2]. Mist the nest regularly or use a moisture chamber until you learn how fast your setup dries out. Good ventilation prevents stagnant air and mold, but avoid strong drafts that dry the nest out too quickly. Balance is key, damp but not wet, ventilated but not dry.

Behavior and Defense

Polyrhachis murina is generally calm and not overly aggressive ^[2]. They will forage actively during the day and night once established. Remember that Formicinae ants lack a functional sting. Instead, they bite and spray a stream of concentrated formic acid from an acidopore to defend themselves ^[2]. Handle them carefully and keep the outworld secure. Colony growth is unconfirmed, but expect a steady build-up over time.

Frequently Asked Questions

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References