Polyrhachis noesaensis

Polyrhachis noesaensis

Polyrhachis noesaensis is a medium-sized ant belonging to the subgenus Myrma, characterized by its distinctive spines on the thorax and dark coloration. Workers measure approximately 6-8mm, with the genus commonly known as 'spiny ants' due to their prominent spines. This species is native to the Indomalaya region, found across Borneo, Indonesia, Malaysia, and the Philippines, where it inhabits tropical rainforest environments ^[1][2]. The species was originally described as a variety of Polyrhachis villipes by Forel in 1915 and was elevated to full species status by Kohout in 1998. Colonies in the wild typically contain around 155 workers on average, though they can range from just 2 to nearly 400 individuals ^[3].

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Tropical rainforest regions of Borneo, Indonesia, Malaysia, and the Philippines. Found at various locations in the Maliau Basin Conservation Area including Ginseng Camp, Agathis Camp, and Maliau Falls ^[1][2].
• Colony Type: Single-queen (monogyne) colonies based on typical Polyrhachis patterns. Colonies in the wild have been observed with replacement reproductives present in some situations.
  • Colony: Monogyne
  • Founding: Claustral
• Size & Growth:
  • Queen: Estimated 10-12mm based on genus patterns for Myrma subgenus
  • Worker: 6-8mm based on genus descriptions
  • Colony: Up to approximately 400 workers ^[3]
  • Growth: Moderate, based on typical Polyrhachis development
  • Development: 8-12 weeks estimated based on related Polyrhachis species (Development time is estimated from genus-level data as species-specific timing has not been studied)
• Antkeeping:
  • Temperature: Keep at 24-28°C, which matches their tropical rainforest origin. A slight temperature gradient allows workers to self-regulate.
  • Humidity: Tropical species requiring high humidity around 70-85%. Keep the nest substrate consistently moist but not waterlogged. Regular misting helps maintain appropriate levels.
  • Diapause: No, as a tropical species, they do not require hibernation. Maintain consistent warm conditions year-round.
  • Nesting: In the wild, Polyrhachis (Myrma) species often nest in vegetation, under bark, or in hollow twigs. In captivity, a Y-tong (AAC) nest or naturalistic setup with tight chambers works well. Provide some vertical space as they are somewhat arboreal.
• Behavior: Polyrhachis ants are generally calm and not overly aggressive, though they will defend their nest if threatened. Workers are active foragers that search for food both on the ground and on vegetation. They have a functional acidopore and can spray formic acid as a defense. Escape prevention is important due to their moderate size, standard barriers work well but ensure lids are secure.
• Common Issues: tropical humidity requirements mean mold can develop if ventilation is poor, balance airflow carefully, colonies may stress if temperatures drop below 22°C, keep them warm, wild-caught colonies may carry parasites from their natural habitat, quarantine and observe new colonies, smaller colonies are vulnerable to stress during relocation, minimize disturbances until established

Housing and Nest Setup

Polyrhachis noesaensis does well in a Y-tong (AAC) acrylic nest or a naturalistic setup. Since they come from tropical rainforest environments, they need consistent warmth and humidity. A test tube setup can work for founding colonies, but transfer to a proper nest once the colony reaches 20-30 workers. The nest should have chambers sized appropriately for their worker size of 6-8mm. Provide a water reservoir to maintain humidity, and consider adding a small outworld area where foragers can search for food. Some keepers successfull use a combination of test tube for the nest chamber connected to a foraging area. ^[1][2]

Feeding and Diet

Like most Polyrhachis species, these ants are omnivorous. They accept sugar sources readily, offer sugar water, honey, or diluted honey water as a constant energy source. For protein, provide small insects such as fruit flies, small crickets, mealworms, or other appropriately sized prey. In their natural habitat, they forage for honeydew from aphids and scale insects, as well as small arthropods. Feed protein sources 2-3 times per week, and keep sugar water available at all times. Remove uneaten prey after 24-48 hours to prevent mold. ^[3]

Temperature and Humidity Management

As a tropical species from Borneo and surrounding regions, P. noesaensis requires warm conditions. Keep the nest area at 24-28°C. A heating cable on one side of the nest can create a temperature gradient, but avoid direct heat that could dry out the nest too quickly. Humidity should be maintained at 70-85%. Use a water reservoir connected to the nest or regular light misting to achieve this. The substrate or nest material should feel consistently moist but never waterlogged. Poor humidity can lead to brood death and colony decline. ^[1][2]

Behavior and Foraging

Workers of Polyrhachis noesaensis are active foragers that will search for food both on the ground and on vegetation, reflecting their arboreal tendencies in the wild. They are generally non-aggressive toward keepers but will defend their nest if threatened. Like other Formicinae, they possess an acidopore and can spray formic acid as a defense mechanism, though this is rarely a concern for keepers. Colony activity increases with warmer temperatures, and workers will become more active in searching for food. They are moderate in size, so standard escape prevention measures work well, but ensure all connections between nest and outworld are secure. ^[3]

Colony Growth and Development

Colonies in the wild have been documented with an average of around 155 workers, though some colonies can reach nearly 400 individuals ^[3]. The founding queen seals herself in a claustral chamber and raises the first workers alone, living off her stored fat reserves until the nanitic (first) workers emerge. Development from egg to worker is estimated at 8-12 weeks based on related Polyrhachis species, as specific timing for this species has not been studied. Growth is moderate, colonies typically take several months to reach 50 workers and may take a year or more to reach larger sizes. Patience is key with this species.

Seasonal Care

As a tropical species from Southeast Asia, Polyrhachis noesaensis does not require hibernation or diapause. Maintain consistent warm temperatures and humidity year-round. Avoid any cooling periods that might simulate winter, this can stress or kill the colony. Room temperature in most homes (around 20-22°C) may be too cool, so additional heating is often necessary. Keep the colony away from air conditioning vents, drafts, and windows that get cold at night. Consistent conditions lead to the best colony growth and longevity. ^[1][2]

Frequently Asked Questions

References