Polyrhachis smithersi

Polyrhachis smithersi

Polyrhachis smithersi is a large, striking ant species native to the Australian Capital Territory. Workers measure 6.6-7.4mm with a distinctive black body contrasted by orange-red mandibles, legs, and reddish-brown gaster. They belong to the subgenus Campomyrma, a group known for their spiny petioles and arboreal habits. The species was only described in 2012 and remains known from a handful of specimens collected at night on Eucalyptus tree trunks in dry open forest ^[1]. This is a nocturnal, tree-dwelling ant with a limited known range.

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Australian Capital Territory, Australia. Found in dry open forest, specifically foraging on Eucalyptus tree trunks at night ^[1][2].
• Colony Type: Colony structure is unconfirmed. Only a few workers and one queen have been collected, all from night foraging on tree trunks.
• Size & Growth:
  • Queen: ~7.5mm ^[1]
  • Worker: 6.6-7.4mm ^[1]
  • Colony: Unknown, only small numbers collected
  • Growth: Unknown, no colony development data available
  • Development: Unconfirmed, no direct observations. Based on typical Polyrhachis patterns, expect 6-10 weeks at warm temperatures. (No published data on development. Related Polyrhachis species typically take 6-10 weeks from egg to worker at 24-28°C.)
• Antkeeping:
  • Temperature: Keep around 24-28°C. This matches their Australian open forest origin and supports activity in a tropical-style setup. A slight temperature gradient allows them to regulate.
  • Humidity: Moderate humidity around 50-70%. These are arboreal ants from dry open forest, so they prefer drier conditions than many tropical species. Ensure some moisture is available but avoid constant dampness.
  • Diapause: Likely required. Australian temperate ants typically need a winter rest period. Reduce temperature to 15-18°C for 2-3 months during austral winter (roughly June-August in the Southern Hemisphere).
  • Nesting: Provide a vertically-oriented nest or formicarium since they naturally forage on tree trunks. Y-tong or acrylic nests work well. Include climbing structures and bark or cork to simulate their arboreal habitat.
• Behavior: Nocturnal and arboreal, they forage at night on tree trunks in the wild. Workers are moderately sized and likely moderately aggressive when defending the colony. They may be less aggressive than some Polyrhachis species. Escape prevention should be moderate, their size makes them moderate escape risks. They likely communicate through chemical signals and may use tandem running to recruit workers to food sources.
• Common Issues: limited data means care is based on genus-level inference rather than species-specific research, nocturnal habits may make them less active during typical keeper observation hours, hibernation requirements are inferred but not confirmed for this species, only known from a few specimens so colony size potential is unknown, wild-caught colonies may be difficult to establish due to limited distribution

Nest Preferences and Housing

Polyrhachis smithersi is an arboreal species that forages on tree trunks in the wild. In captivity, provide a vertically-oriented setup that mimics their natural environment. Y-tong (acrylic) nests work well, or you could use a naturalistic setup with cork bark or similar climbing structures. Include multiple chambers at different heights and ensure the nest has good ventilation. Since they're nocturnal foragers, place the nest in a location with natural light cycles and avoid disturbing them during their active night hours. The species is moderately large (6-7mm workers), so standard formicarium chambers work well. Avoid overly humid conditions, these ants come from dry open forest and prefer their nest area to stay relatively dry while having access to water elsewhere. ^[1][2]

Feeding and Diet

Polyrhachis ants are typically omnivorous, feeding on honeydew, nectar, and small insects in the wild. For this species, offer a varied diet including sugar water or honey as an energy source, and protein sources like small crickets, mealworms, or other insects. Since they're nocturnal foragers, place food in the outworld in the evening and check the next morning. Based on related Polyrhachis species, they likely accept both sweet liquids and protein prey. Feed protein 2-3 times per week, and keep a constant sugar source available. Remove uneaten prey after 24-48 hours to prevent mold. Fresh water should always be available.

Temperature and Seasonal Care

Maintain temperatures around 24-28°C during the active season. This range reflects their Australian origin in the ACT region, where summer temperatures regularly exceed this range. A temperature gradient of 24-30°C across the setup allows the ants to choose their preferred zone. During winter (roughly June-August in the Southern Hemisphere), reduce temperatures to 15-18°C to provide a dormancy period. This winter rest is typical for Australian temperate ants and helps maintain colony health. Monitor colony behavior, if workers become sluggish and cluster together, the temperature may be too low. If they avoid the heated areas, reduce temperature slightly. Avoid sudden temperature changes. ^[1]

Behavior and Colony Dynamics

This species is nocturnal, with all known specimens collected while foraging on Eucalyptus tree trunks at night. Workers are moderately sized and likely use chemical communication to coordinate foraging and defend the colony. Based on related species in the subgenus Campomyrma, they probably establish moderate-sized colonies with a single queen. Workers may show moderate aggression when the nest is disturbed. The species has distinctive spines on the petiole (the narrow waist section) which they may use for defense. Colonies are likely to be slower-growing than many tropical species due to the temperate climate of their origin. Be patient with colony development, it may take several months to see significant growth after the first workers emerge. ^[1]

Frequently Asked Questions

References