Polyrhachis saevissima

Polyrhachis saevissima

Polyrhachis saevissima is a striking arboreal ant species native to Southeast Asia and the Indo-Malayan region, found across Borneo, India, Indonesia, Malaysia, the Philippines, Singapore, and Sulawesi ^[1]. Workers are small at approximately 4-4.2mm, featuring a distinctive black body covered in a thin silky grayish pile (cinereous pile) and characteristic spines on the thorax, metathorax, and peduncle ^[2]. The abdomen is notably rounded and globose. This species belongs to the armata species-group within the subgenus Myrmhopla, and is known for its arboreal lifestyle, nesting in trees and using silk to construct protective structures ^[3].

What makes P. saevissima particularly interesting is its use of silk in nest building, a behavior shared with other Myrmhopla species. These ants are diurnal, actively foraging during daylight hours ^[4], and they inhabit diverse forest environments from mangrove swamps to natural forests and agroforestry areas, ranging up to 1200m in elevation ^[1]. Their spiny morphology serves as effective defense against predators.

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Tropical Southeast Asia and Indo-Malayan region, found in Borneo, India, Indonesia, Malaysia, Philippines, Singapore, and Sulawesi. Inhabits diverse forest types including mangrove, natural forest, and agroforestry areas, from sea level up to 1200m elevation ^[1][3].
• Colony Type: Colony structure is not well documented in scientific literature. Based on typical Polyrhachis patterns, likely monogyne (single queen) but may exhibit flexibility. Further research needed to confirm.
  • Founding: Claustral
• Size & Growth:
  • Queen: Unconfirmed in primary literature, estimated 6-8mm based on related Polyrhachis species in the armata-group
  • Worker: Approximately 4-4.2mm ^[2]
  • Colony: Likely moderate, several hundred workers based on genus patterns
  • Growth: Moderate, estimated based on tropical arboreal ant patterns
  • Development: Estimated 6-8 weeks at optimal tropical temperatures (25-28°C) (Direct development data unavailable for this species, estimates based on typical Polyrhachis development patterns. Pupal cocoons are present in this species ^[3].)
• Antkeeping:
  • Temperature: Keep at 24-28°C, these are tropical ants requiring warm, stable conditions. A gentle gradient allowing workers to self-regulate is ideal. Room temperature within this range is acceptable, otherwise use a heating cable on one side of the nest.
  • Humidity: High humidity required, aim for 70-85%. Their natural arboreal habitat in tropical forests is consistently humid. Use moist substrate in the nest area and maintain hydration through water tubes. Avoid both drying out and waterlogging.
  • Diapause: No, these are tropical ants that do not require hibernation. Maintain warm temperatures year-round. A slight reduction in activity during cooler months is normal but they remain active.
  • Nesting: Arboreal species requiring vertical space. In captivity, they do well in Y-tong (AAC) nests or plaster nests with chambers scaled to their small size. Provide twigs, bark pieces, or similar materials they can use for silk nest construction. Avoid fully enclosed test tube setups, they prefer more open, arboreal-style housing.
• Behavior: Polyrhachis saevissima is a diurnal, arboreal forager with moderate aggression when defending the colony ^[4]. Workers are active foragers during the day, searching for honeydew, nectar, and small insects in trees and vegetation. They have moderate escape risk due to their small size, ensure enclosures have no gaps. As Formicinae, they possess formic acid for defense but are not typically aggressive toward keepers. They are not known for stinging.
• Common Issues: tropical temperature requirements mean cold drafts or air conditioning can stress or kill colonies, small size means escapes are possible without proper barrier maintenance, arboreal nature requires vertical space, flat horizontal nests may not be ideal, high humidity needs can lead to mold if ventilation is poor, wild-caught colonies may harbor parasites that can cause colony failure in captivity

Housing and Nest Setup

Polyrhachis saevissima requires housing that reflects their arboreal nature. Unlike ground-nesting ants, these spiny ants prefer vertical space and will do best in Y-tong (AAC) nests or plaster formicaria with multiple chambers. You can also provide naturalistic setups with twigs, bark pieces, and leaves where they can construct silk nests similar to their natural habitat ^[3]. The nest should have good ventilation while maintaining humidity, this is critical to prevent mold. Avoid fully enclosed test tube setups as they don't suit the arboreal lifestyle. The outworld should include climbing structures and plants where workers can forage. Use a water tube for hydration and ensure the nest substrate stays moist but never waterlogged.

Feeding and Diet

In the wild, Polyrhachis saevissima forages for honeydew from aphids and scale insects, nectar from flowers, and small insects and arthropods ^[1]. In captivity, offer a varied diet including sugar water or honey as a constant carbohydrate source. For protein, provide small insects like fruit flies, small crickets, or mealworms. They are moderate feeders, offer protein 2-3 times per week and keep sugar sources available at all times. Remove uneaten prey after 24-48 hours to prevent mold. Some keepers report they readily accept jelly and commercial ant sweets. Observe your colony's preferences and adjust feeding frequency accordingly.

Temperature and Seasonal Care

As tropical arboreal ants from Southeast Asia, P. saevissima requires warm temperatures year-round. Keep the nest area at 24-28°C, with a slight gradient allowing workers to choose their preferred temperature zone. A heating cable placed on one side of the nest can create this gradient. They do not require hibernation or diapause, maintaining consistent tropical conditions is key. Avoid placing the colony near air conditioning vents, drafty windows, or cold walls. During cooler winter months, ensure heating is maintained. Signs of cold stress include lethargy, clustering, and reduced foraging. Room temperature within their preferred range is ideal, if your home is cooler, supplemental heating is necessary.

Behavior and Colony Dynamics

Polyrhachis saevissima is a diurnal species, workers actively forage during daylight hours ^[4]. They are arboreal by nature, spending most of their time in trees and vegetation rather than on the ground. Workers are moderately aggressive when defending the colony but not typically dangerous to keepers. As members of the Formicinae subfamily, they can spray formic acid as a defense mechanism, though this species is not known for particularly aggressive behavior toward humans. Colony growth is moderate, expect several months before the first workers (nanitics) appear after founding, and several years to reach a mature colony size of several hundred workers. Queens are relatively long-lived, and colonies can persist for many years with proper care.

Escape Prevention and Handling

While not extremely small (workers are approximately 4mm), P. saevissima can still escape through small gaps. Use tight-fitting lids on any enclosures and ensure any ventilation holes are covered with fine mesh. Fluon applied to the edges of formicaria can create an effective barrier. When observing or working with the colony, do so in a contained area. These ants are not harmful to humans, they may spray formic acid if handled roughly, but this causes only mild irritation. If you need to move or transport the colony, do so gently and avoid shaking or disturbing the nest significantly.

Frequently Asked Questions

References