Polyrhachis gibbosa

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Sri Lanka (Indomalaya Region) – lowland wet forest ^[1]
• Colony Type: Unconfirmed – most Polyrhachis are single-queen (monogyne), but no direct data for this species
• Size & Growth:
  • Queen: Not described – based on worker size (~6 mm) and typical Polyrhachis ratios, estimated around 8-10 mm (inferred from genus patterns)
  • Worker: 5.85-6.35 mm ^[2][3]
  • Colony: Not documented – Polyrhachis colonies typically reach several hundred to a few thousand workers (inferred from genus)
  • Growth: Moderate – inferred from tropical Formicinae
  • Development: Likely 6-10 weeks at optimal temperatures (24-28°C) – inferred from related species (No direct data for P. gibbosa, estimate based on other Polyrhachis and Formicinae)
• Antkeeping:
  • Temperature: Keep at 24-28°C. As a tropical Sri Lankan species, it needs consistent warmth. A heating cable on one side of the nest creates a gradient (inferred from genus patterns).
  • Humidity: Moderate to high – nest substrate should feel moist but not waterlogged, with some drier patches. Lowland wet forests are humid, avoid letting the nest dry out (inferred from habitat).
  • Diapause: No – tropical species, no winter rest needed. Keep warm year-round.
  • Nesting: Likely nests in rotting wood, under bark, or in vegetation. In captivity, Y-tong (AAC), plaster, or earth nests work. Provide vertical structures like twigs or bark pieces (inferred from arboreal Polyrhachis habits).
• Behavior: Generally calm and not aggressive toward keepers. Workers forage actively and may explore the outworld. If threatened, they bite and spray formic acid (subfamily Formicinae trait). Escape risk is moderate due to ~6 mm size – standard barriers (fluon, mineral oil) are enough. Probably omnivorous, accepting sugars and insects.
• Common Issues: tropical species may decline if temperatures drop below 22°C – maintain stable warmth, high humidity needs can cause mold in the nest if ventilation is poor – provide airflow, queens are rarely available in the hobby – wild-caught colonies may be the only option, founding queens and colonies are poorly documented, so unexpected problems may arise

Housing and Nest Setup

Based on general Polyrhachis preferences, P. gibbosa does well in Y-tong (AAC) or plaster nests that hold moisture well. The nest should stay warm and humid – a test tube with water section works for founding. Once the colony grows, add an outworld with a tight-fitting lid. Because these ants are agile climbers, apply fluon or PTFE barrier around the edges. They likely appreciate vertical elements like bark or twigs attached to the nest walls, mimicking an arboreal or semi-arboreal lifestyle.

Feeding and Diet

Like most Polyrhachis, P. gibbosa is probably an omnivore. Provide a constant source of carbohydrates – sugar water, honey, or diluted maple syrup on a cotton ball. For protein, offer small insects such as fruit flies, small crickets, or mealworms. Feed protein every two to three days, removing leftovers after a day to avoid mold. Fresh water should always be available, either in a test tube or a shallow dish.

Temperature and Humidity Management

Tropical species like P. gibbosa need steady warmth. Keep the nest area at 24-28°C (75-82°F). A small heating mat under part of the nest creates a temperature gradient. Humidity should be high – the nest substrate should feel damp but not dripping. Use a hygrometer to monitor, if the air is too dry, cover part of the ventilation or add a moist sponge. Good airflow is still important to prevent mold.

Colony Development and Growth

Exact growth timeline for P. gibbosa is unknown. Based on other Polyrhachis, a queen likely starts laying eggs within a few weeks of mating, sealing herself in a claustral chamber. First workers (nanitics) probably appear after 6-10 weeks at optimal temperature. Colonies grow moderately, you may see several dozen workers after a year, then several hundred over the next year with good care.

Behavior and Temperament

Polyrhachis gibbosa is a calm, diurnal forager. Workers move at a moderate pace and rarely show aggression unless the nest is directly disturbed. Their defense is biting and spraying formic acid – they cannot sting. This is generally harmless to humans but can irritate sensitive skin. The silvery pubescence makes them attractive to watch, and they often forage openly during the day.

Frequently Asked Questions

Report an Issue

The current care sheet is based fully on literature. See inconsistencies, or something that's incorrect? Please report here, it will be resolved after review from an admin. Contributing to the blogs tab also helps providing information, to make us be able to further improve the caresheets. Thank you for your support!

References