Polyrhachis robusta

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Papua New Guinea, Northern District and Owen Stanley Range, at 500 to 3000 feet, in rotting logs and felled trees ^[1].
• Colony Type: Colony structure is unconfirmed, as no specific data is available.
• Size & Growth:
  • Queen: Approximately 13.51 mm total length ^[1]
  • Worker: 12.65-13.00 mm total length ^[1]
  • Colony: Unknown, no data on colony size.
  • Growth: Moderate, inferred from genus patterns.
  • Development: Estimated 6-10 weeks at optimal temperature. (Development time may vary with temperature.)
• Antkeeping:
  • Temperature: Keep warm, roughly 24-28°C, as they are from tropical Papua New Guinea ^[1].
  • Humidity: Keep nest substrate consistently moist but not waterlogged, as they live in humid forests ^[1].
  • Diapause: No, as a tropical species.
  • Nesting: They nest in rotting wood, so provide wood-like nests such as Y-tong or plaster.
• Behavior: Generally calm and non-aggressive. As Formicinae ants, they can spray formic acid when threatened, but they are not known to be defensive.
• Common Issues: high humidity management is critical to prevent colony failure, founding colonies can be challenging due to limited knowledge, tropical species may struggle in cold climates, limited availability in the hobby, wild-caught colonies may harbor parasites

Housing and Nest Setup

Polyrhachis robusta nests in rotting wood in the wild ^[1]. In captivity, they may adapt to wood-like nests such as Y-tong (AAC) or plaster nests. Keep the nest chambers snug to mimic their natural habitat. Provide a foraging area with substrate and hiding spots.

Temperature and Humidity Requirements

Keep temperatures around 24-28°C, as they are from tropical Papua New Guinea ^[1]. Maintain high humidity by keeping the nest substrate moist but not waterlogged ^[1].

Feeding and Diet

They are generalist foragers. Offer protein sources like small insects 2-3 times per week, and keep sugar water available continuously.

Colony Development and Growth

The queen is larger than workers, with a size difference noted in the research ^[1]. First workers may be smaller but substantial. Growth rate is moderate, and colonies may reach several hundred workers over time.

Behavior and Handling

Workers are generally calm and not aggressive. Their large size makes escape prevention straightforward with standard barriers. As Formicinae ants, they can spray formic acid, but this species is docile.

Seasonal Care

As a tropical species, they do not require diapause. Maintain stable warm and humid conditions year-round.

Frequently Asked Questions

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References