Polyrhachis solmsi

Polyrhachis solmsi

Polyrhachis solmsi is a medium-sized arboreal ant native to the Indonesian archipelago, found primarily in Java, Borneo, and Sulawesi ^[1][2]. Workers measure approximately 9mm and feature distinctive dorsal spines on the thorax and metanotum, including two strong triangular teeth on the metanotum ^[2]. Like all ants in the subfamily Formicinae, this species lacks a stinger and instead defends itself by spraying formic acid ^[3].

What makes P. solmsi particularly interesting is its nesting behavior, it builds tiny carton nests on the underside of tree leaves, using silk and plant material to construct protective structures ^[2][4]. The species was originally described as Polyrhachis solmsi before being synonymized, and currently exists as two subspecies including P. solmsi multicella ^[3].

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Native to the Indonesian archipelago, specifically Java, Borneo, and Sulawesi. This is a tropical arboreal species that nests in trees, building carton nests on the underside of leaves ^[2][5].
• Colony Type: Colony structure is not fully confirmed. Founding colonies have been observed with multiple dealate queens in early-stage nests, suggesting possible polygynous founding or pleometrosis ^[2]. Further research needed to confirm whether established colonies maintain multiple queens.
  • Founding: Claustral
• Size & Growth:
  • Queen: Larger than workers, exact measurements unconfirmed ^[2]
  • Worker: Approximately 9mm ^[2]
  • Colony: Unknown, no documented colony size in research
  • Growth: Moderate, estimated based on related Polyrhachis species
  • Development: Estimated 6-10 weeks at tropical temperatures based on genus-level data for related species (Development time is estimated as no specific study exists for this species. Pupal cocoons are present, which is notable as some Formicinae species lack cocoons ^[4].)
• Antkeeping:
  • Temperature: Keep at 24-28°C, these are tropical ants requiring warm conditions. A heating cable on one side of the nest creates a suitable gradient ^[3].
  • Humidity: Moderate to high humidity (60-80%). As an arboreal species, they prefer humid conditions but the nest should have good ventilation to prevent mold in carton structures ^[3].
  • Diapause: No, as a tropical species, they do not require hibernation. Maintain warm temperatures year-round ^[3].
  • Nesting: Arboreal setup is essential. These ants build carton nests in nature, so provide vertical space with plants, branches, or cork bark. A naturalistic setup with live plants works well. Test tubes can work for founding colonies but will need to transition to arboreal space as the colony grows ^[2][4].
• Behavior: Generally peaceful but defensive. Workers are active foragers that will explore their environment. As Formicinae, they can spray formic acid when threatened, this is irritating but not dangerous to humans. Escape risk is moderate due to their size, standard barrier methods work well. They are arboreal by nature and will utilize vertical space extensively ^[3][4].
• Common Issues: tropical temperature requirements mean cold rooms will cause colony decline, arboreal setup requires more space and complexity than ground-nesting species, carton nests can develop mold if humidity is too high without ventilation, multiple founding queens may fight if not enough space is provided during colony establishment, wild-caught colonies may carry parasites that can devastate captive populations

Nest Preferences and Housing

Polyrhachis solmsi is an arboreal species, meaning it naturally lives in trees and builds nests above ground rather than in soil ^[4]. In the wild, they construct small carton nests on the underside of leaves using a mixture of plant fibers and silk-like material ^[2]. The nests are relatively simple, dome-shaped structures that house the queen(s) and developing brood.

For captive care, you'll need to replicate this arboreal lifestyle. A naturalistic setup with live plants, branches, and cork bark works best. The ants will build their own carton structures if given appropriate materials. For simpler setups, you can use acrylic nests with horizontal chambers, but include branches or other structures for them to walk on. Test tubes can work for founding colonies but will quickly become inadequate as the colony grows, these ants need vertical space.

Keep the nest humid but ensure good ventilation. Stagnant, overly moist air leads to mold that can destroy their carton nests. A fine mist spray bottle works well for rehydration without flooding the setup ^[5].

Feeding and Diet

Polyrhachis ants are omnivorous, similar to their close relatives in the genus Camponotus. In captivity, they readily accept sugar sources such as honey water, sugar water, or commercial ant nectar. For protein, offer small insects like fruit flies, small crickets, mealworms, or other appropriately sized prey.

Feed sugar sources constantly, a small dish or cotton ball with honey water should be available at all times. Protein should be offered 2-3 times per week, with the amount scaled to your colony size. Remove uneaten prey after 24-48 hours to prevent mold. These ants are foragers and will send workers out to collect food, so ensure they have easy access to feeding stations.

As a tropical species, they may have higher energy requirements, maintaining warm temperatures year-round means their metabolism stays active and they consume food regularly throughout the year rather than having seasonal slowdowns. ^[3]

Temperature and Seasonal Care

As a tropical Indonesian species, Polyrhachis solmsi requires warm temperatures between 24-28°C (75-82°F). They do not tolerate cool conditions, temperatures below 20°C can stress the colony and slow or stop brood development entirely. Room temperature may be insufficient in cooler climates, so use a heating cable or heat mat to maintain warmth.

Place the heating element on one side of the nest to create a temperature gradient, allowing ants to regulate their own body temperature by moving between warmer and cooler areas. Never place heat directly under water reservoirs as it causes rapid evaporation.

Unlike temperate species, P. solmsi does not require hibernation or diapause. Maintain consistent tropical conditions year-round. This means higher year-round food consumption compared to species that slow down in winter. Monitor humidity as heating elements can dry out the nest, rehydrate when the substrate surface appears dry ^[3].

Defense and Handling

Polyrhachis solmsi belongs to the subfamily Formicinae, which means they lack a functional stinger. Instead, like other Formicinae including Camponotus and Lasius, they defend themselves by spraying formic acid, a irritating chemical that can cause discomfort if it contacts skin or eyes ^[3].

The spray is not dangerous to humans but can be unpleasant. When handling these ants or working with the colony, work in a well-ventilated area and avoid getting formic acid on your skin. Wash hands thoroughly after any contact.

In terms of temperament, these ants are not particularly aggressive but will defend their nest if threatened. Workers are moderately active and good at exploring their environment. Their moderate size (9mm workers) makes them easier to handle than many tiny ant species, and standard escape prevention methods work well.

Colony Founding

Colony founding in Polyrhachis solmsi has been observed in the wild. One study documented a small carton nest in early stages of formation containing two dealate (wingless) queens ^[2]. This suggests either pleometrosis (multiple queens founding together) or sequential queen adoption.

Like most Formicinae, P. solmsi is likely claustral, the queen seals herself in a chamber and lives off her stored fat reserves while raising the first brood. She does not leave to forage during founding. The first workers (nanitics) are typically smaller than normal workers but will begin expanding the nest and foraging once emerged.

For captive founding, provide a claustral setup, a test tube or small container with moist substrate, kept warm and undisturbed. The queen will seal herself in and emerge with her first workers 6-10 weeks later, depending on temperature. If you have multiple founding queens, monitor for aggression as colonies establish.

Frequently Asked Questions

References