Polyrhachis lydiae

Polyrhachis lydiae

Polyrhachis lydiae is a medium-sized ant native to eastern Australia, easily recognized by its striking metallic green to greenish-black coloration with a distinctive reddish-brown patch on the front of its pronotum (the middle body section). This color combination is unique among Australian Polyrhachis species ^[1]. Workers measure 5.64-6.65mm, while queens are larger at 7.21-7.51mm ^[1]. The species belongs to the schenckii species-group within the subgenus Hagiomyrma. In the wild, these ants nest in the ground with entrances hidden under stones or tufts of grass, commonly found in open eucalypt forests and savannah woodlands along the eastern Australian coast from Townsville to near Newcastle ^[1][2].

This is a ground-nesting species that builds subterranean colonies. Like other Formicinae ants, they lack a functional stinger but can defend themselves by biting and spraying formic acid. They are known hosts of the zombie-ant fungus Ophiocordyceps nooreniae, though this is not a concern for captive colonies ^[3].

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Eastern Australia, from Townsville in north Queensland to just north of Newcastle in New South Wales. Found in open eucalypt forests and savannah woodlands ^[1][2].
• Colony Type: Likely monogyne (single-queen colonies) based on typical Polyrhachis patterns. Colony size data is limited but related species typically reach several hundred workers.
  • Colony: Monogyne
  • Founding: Claustral
• Size & Growth:
  • Queen: 7.21-7.51 mm ^[1]
  • Worker: 5.64-6.65 mm ^[1]
  • Colony: Estimated several hundred workers based on related species
  • Growth: Moderate, estimated 6-10 weeks from egg to first worker at optimal temperature
  • Development: 6-10 weeks (estimated based on related Formicinae species) (Development time is inferred from genus-level data since specific development studies are not available for this species)
• Antkeeping:
  • Temperature: Keep at 24-28°C. They are a warm-climate Australian species that benefits from moderate heating. A heating cable on one side of the nest creates a suitable gradient.
  • Humidity: Moderate humidity around 50-70%. These ground-nesting ants prefer substrate that is slightly moist but not waterlogged. Allow some drying between waterings.
  • Diapause: Likely minimal or no true diapause, Australian tropical/subtropical species may slow down in cooler months but probably don't require hibernation like temperate species.
  • Nesting: Naturalistic setup works well given their ground-nesting habits. A substrate-based nest or Y-tong with soil chambers mimics their natural subterranean nests. Keep the nest area dark as they prefer dim conditions.
• Behavior: Generally calm temperament but will defend the colony if threatened. Like other Formicinae, they can bite and spray formic acid as defense. Workers are moderately active foragers. Escape risk is moderate, their medium size means standard formicarium barriers are usually sufficient, but check for gaps.
• Common Issues: colonies may slow significantly if temperatures drop below 20°C, ground-nesting species needs appropriate substrate depth for nesting, escape prevention should be checked regularly as workers can squeeze through small gaps, limited availability in the antkeeping hobby, may be difficult to source, zombie-ant fungus is a natural pathogen but unlikely to affect captive colonies

Housing and Nest Setup

Polyrhachis lydiae is a ground-nesting species that prefers subterranean nests. In captivity, a naturalistic setup with a soil substrate works best, this allows the ants to dig their own chambers like they would in the wild. Use a substrate depth of at least 3-5cm to accommodate their nesting behavior. Alternatively, a Y-tong (AAC) nest with narrow chambers can work, but provide some soil or damp substrate in the outworld for foraging opportunities. Keep the nest area relatively dark, these ants naturally nest underground and prefer dim conditions. Include stones or decorations in the outworld that can hide nest entrances, mimicking their natural habitat under stones or grass tufts ^[1].

Feeding and Diet

Like most Polyrhachis species, these ants are omnivorous. Offer a varied diet including sugar sources (honey water, sugar water) and protein (small insects like fruit flies, mealworms, crickets). They will likely accept honeydew as well if you keep aphids. Feed them every 2-3 days, removing any uneaten prey after 24 hours. A constant sugar water supply is recommended. Because they are medium-sized ants, their prey items can be slightly larger than what you'd offer to tiny ants, but keep portions reasonable.

Temperature and Heating

As an Australian species from a warm climate, Polyrhachis lydiae benefits from temperatures in the 24-28°C range. Room temperature may be sufficient in warmer homes, but a heating cable or small heat mat on one side of the nest can help maintain optimal conditions. Create a temperature gradient so workers can choose their preferred spot. Avoid temperatures below 20°C for extended periods, this species is not adapted to cold conditions and colonies may become sluggish or stop brood development entirely. Monitor colony behavior to find the ideal temperature for your specific setup.

Humidity and Water

These ants prefer moderate humidity around 50-70%. Keep the nesting substrate slightly moist but not waterlogged, the substrate should feel damp but you shouldn't see standing water. Allow the substrate to dry partially between waterings rather than keeping it constantly wet. A water tube in the outworld provides drinking water. Mist the outworld occasionally but avoid excessive moisture in the nest area as this can lead to mold problems.

Behavior and Defense

Polyrhachis lydiae has a generally calm temperament and is not particularly aggressive toward keepers. However, like all Formicinae ants, they can defend themselves by biting and spraying formic acid. The formic acid spray is their primary chemical defense and may cause skin irritation in sensitive individuals. When working with the colony, move slowly and avoid disturbing the nest directly. Workers are moderately active and will forage in the outworld for food. They are not particularly fast-moving, making them relatively easy to observe.

Frequently Asked Questions

References