Polyrhachis dolomedes

Polyrhachis dolomedes

Polyrhachis dolomedes is a medium-sized arboreal ant belonging to the subgenus Myrmatopa. Workers measure around 6-7mm with a distinctive dark coloration and spiny petiole characteristic of the genus. This species is found across the Australasian and Indomalayan regions, including New Guinea, Borneo, Indonesia, Malaysia, and Thailand ^[1]. The species was originally described by Frederick Smith in 1863 from specimens collected on Seram Island, Indonesia, with later synonymization of P. schang amboinae confirmed in 2012 ^[2]. Unlike many ground-nesting ants, P. dolomedes is arboreal, nesting in trees and using silk to construct protective chambers rather than forming cocoons ^[3].

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Tropical rainforests of Southeast Asia and Australasia, from sea level to mid elevations (found at 200-900m in New Guinea). Nests arboreally in trees, recorded in undisturbed forest ^[4]. Type localities include Seram and Ambon islands in Indonesia ^[2][5].
• Colony Type: Colony structure is not well documented in scientific literature. Based on subgenus Myrmatopa patterns, likely monogyne (single queen) colonies. Ergatoid (wingless reproductive) females have been observed in related populations ^[5].
  • Colony: Monogyne
  • Founding: Claustral
• Size & Growth:
  • Queen: Estimated 8-10mm based on genus patterns, direct measurements not available
  • Worker: Approximately 6-7mm based on type specimen descriptions ^[1]
  • Colony: Unknown for this specific species, Polyrhachis colonies typically reach several hundred workers
  • Growth: Moderate, estimated based on tropical Formicinae patterns
  • Development: Estimated 6-8 weeks at tropical temperatures (25-28°C) (Development time is estimated from related Polyrhachis species, direct measurements for this species are not available)
• Antkeeping:
  • Temperature: Keep at 24-28°C. This is a tropical species requiring warm, stable conditions similar to its natural rainforest canopy habitat ^[3]. A gentle temperature gradient allows ants to regulate their exposure.
  • Humidity: High humidity (70-85%). Arboreal ants from tropical rainforests need moist conditions. Provide a water tube and keep the nest area humid, but ensure ventilation to prevent mold.
  • Diapause: No, as a tropical species, P. dolomedes does not require hibernation. Maintain consistent temperatures year-round.
  • Nesting: Arboreal nesters, they prefer nests that allow climbing and vertical space. Y-tong (AAC) nests or naturalistic setups with twigs/branches work well. They use silk to line their nests rather than spinning cocoons ^[3]. Avoid fully enclosed test tube setups, they do better with some vertical climbing space.
• Behavior: Generally calm and non-aggressive compared to some Polyrhachis species. Workers are active foragers that search for honeydew and small prey in the canopy. They are not known for stinging and pose no danger to keepers. Escape risk is moderate, they can climb well but are not particularly fast or small. Ensure the outworld has smooth barriers as they are agile climbers.
• Common Issues: tropical species is sensitive to temperature drops below 20°C, keep warm, arboreal nature means they need vertical climbing space, flat test tubes are unsuitable, high humidity requirements can lead to mold if ventilation is poor, wild-caught colonies may be stressed from removal from arboreal nests, silk-nesting behavior means they may not accept conventional formicaria without added twigs/branches

Nest Preferences and Housing

Polyrhachis dolomedes is an arboreal species that nests in trees rather than in soil. In captivity, they do best in setups that mimic their natural canopy habitat. Y-tong (AAC) nests work well because they provide smooth walls that prevent escape and allow you to add small twigs or branches for climbing enrichment. Naturalistic setups with cork bark or wooden elements are also suitable. Avoid pure test tube setups, these arboreal ants become stressed without vertical space and climbing opportunities. They use silk to construct and line their nests rather than spinning cocoons for their pupae ^[3]. The nest should be kept humid but with adequate ventilation to prevent mold buildup. Place the nest in a warm area of your setup, as tropical arboreal ants are sensitive to cold.

Feeding and Diet

Like most Polyrhachis species, P. dolomedes is omnivorous with a preference for honeydew and small insects. In captivity, offer a consistent sugar source such as sugar water, honey, or diluted maple syrup. For protein, provide small insects like fruit flies, pinhead crickets, or mealworms. They are not specialized predators, so a varied diet of protein sources and sugary liquids works well. Feed protein 2-3 times per week, and keep sugar water available at all times. Remove uneaten prey after 24-48 hours to prevent mold. Young colonies may be shy feeders, offer small amounts and observe what they accept.

Temperature and Seasonal Care

As a tropical species from Southeast Asia and New Guinea, P. dolomedes requires warm conditions year-round. Keep the nest area at 24-28°C with minimal temperature fluctuations. Unlike temperate species, they do not enter diapause or hibernation. A small heating cable or mat on one side of the nest can help maintain warmth, but avoid direct heat that could dry out the nest. Room temperature in a heated home is often suitable, but monitor during winter months when ambient temperatures drop. Cold stress is one of the most common issues with tropical arboreal ants, if workers appear sluggish and cluster tightly, the colony may be too cold. ^[7]

Behavior and Colony Dynamics

Polyrhachis dolomedes workers are relatively calm and not particularly aggressive. They are active foragers that will search the outworld for food, and they climb well due to their arboreal lifestyle. The colony will establish a foraging pattern once they settle in. Workers have a spiny petiole (the narrow waist section) which gives them a distinctive appearance, but they are not known for stinging and pose no threat to keepers. The colony will grow gradually, Polyrhachis species are not among the fastest-growing ants, but they are long-lived and colonies can persist for many years with proper care. The queen is likely claustral, sealing herself in to raise the first brood on stored fat reserves. ^[3]

Origin and Natural History

This species was originally described by Frederick Smith in 1863 from specimens collected on Seram Island, Indonesia, part of the Maluku Islands. The type locality was later clarified to include specimens from Ceram (Seram) and Ambon islands ^[2][5]. The species has a broad distribution across the Australasian and Indomalayan regions, recorded from New Guinea, Borneo, Malaysia, and Thailand ^[6]. In New Guinea, they have been found at elevations between 200-900m in tropical rainforest canopies, with nest abundance decreasing at higher elevations ^[7]. They are typically found in undisturbed forest environments ^[4], suggesting they may be sensitive to habitat disturbance.

Frequently Asked Questions

References