Pseudomyrmex rubiginosus

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Tropical rainforests of Colombia, Peru, and western Brazil. This species is an obligate plant-ant that lives inside domatia-bearing trees and shrubs like Triplaris, Tachigali, Pleurothyrium, Gustavia, and Ocotea ^[1][2].
• Colony Type: Likely single-queen (monogyne) colonies based on genus patterns, but this is not confirmed for this species. As a plant-ant, colonies typically inhabit individual plant cavities.
• Size & Growth:
  • Queen: Size data unavailable, total length not recorded in literature. Inferred from related Pseudomyrmex species to be around 5-7 mm.
  • Worker: Size data unavailable, total length not recorded in literature. Inferred from the Pseudomyrmex genus to be around 3-5 mm.
  • Colony: Unknown, based on similar plant-ant species, colonies likely reach up to a few hundred workers at most.
  • Growth: Moderate
  • Development: Estimated 6-8 weeks at warm tropical temperatures (24-28°C), consistent with related species. (Development is likely continuous year-round due to tropical origin. First workers (nanitics) will be smaller than mature workers.)
• Antkeeping:
  • Temperature: Maintain 24-28°C consistently. These are tropical ants that need warmth year-round, temperatures below 20°C can be fatal. Use a heating cable on one side of the nest to create a gradient.
  • Humidity: Keep the nest substrate consistently moist but not waterlogged. Simulate the humid interior of a living plant, test tubes or wet sponges can help. Ensure good ventilation to prevent mold.
  • Diapause: No, this tropical species does not require hibernation. Keep warm year-round.
  • Nesting: Y-tong (AAC) or plaster nests work well. Since these ants are small, provide narrow chambers. A naturalistic setup with hollow stems or a moist substrate can also work. Avoid dry conditions.
• Behavior: Pseudomyrmex rubiginosus workers are fast, alert foragers that hunt individually. They have a well-developed sting and will defend their nest vigorously. Not aggressive toward humans unless provoked, but their sting can be painful. Their small size (under 5 mm) means escape prevention is critical, use fine mesh or PTFE barriers.
• Common Issues: tropical species dies if temperatures drop below 24°C, keep warm year-round, small size makes escape prevention essential, use fine mesh barriers, requires live prey (e.g., fruit flies, small crickets) for brood development, cannot thrive on sugar alone, high humidity needs can cause mold if ventilation is poor, balance moisture with airflow, plant-ant origins may make conventional dry formicaria unsuitable, provide moisture-retaining nest materials

Housing and Nest Setup

Pseudomyrmex rubiginosus does well in Y-tong (AAC) or plaster nests that hold moisture. Since these are small ants, chambers should be narrow, large spaces may make the colony feel insecure. A naturalistic setup with hollow twigs or a moist substrate can mimic their plant-dwelling lifestyle, but this is optional. Test tubes work for founding but may dry out quickly, monitor moisture levels. Always cover the nest to provide darkness, as these ants naturally nest in dark interior cavities ^[1].

Feeding and Diet

These ants are predatory and need live food for brood development. Offer small live insects like fruit flies, pinhead crickets, or small mealworms 2-3 times per week. They will also take sugar water or honey for energy, but protein is essential. Remove uneaten prey after 24 hours to avoid mold. A varied diet with different small arthropods is beneficial. Unlike some ants that survive on sugars alone, Pseudomyrmex require regular protein ^[1].

Temperature and Seasonal Care

Keep the colony at 24-28°C year-round. As a tropical species, they do not tolerate cool conditions. Use a heating cable on one side of the nest to create a warm zone. Room temperature alone may be too low, especially in winter or air-conditioned rooms. No hibernation is needed, these ants are active year-round. Avoid temperature fluctuations and drafts. Consistent warmth is essential for health and growth.

Behavior and Defense

Pseudomyrmex rubiginosus workers are fast, alert foragers that move quickly. They are defensive of their nest and will attack intruders. Like all Pseudomyrmecinae, they have a functional sting and can deliver a painful sting if threatened. They are not aggressive toward humans but will defend when disturbed. Workers forage individually, hunting small prey rather than recruiting in groups. Their relatively good vision helps them navigate plant environments.

Humidity and Water

High humidity (70-85%) is important, these ants come from humid rainforest interiors. Keep the nest substrate moist but not flooded. Rehydrate when the surface starts drying rather than on a fixed schedule. Good ventilation prevents mold, but avoid excessive airflow that dries things out. A water test tube connected to the nest can maintain humidity through evaporation. Watch for condensation, some is good, but pooling water may cause issues.

Frequently Asked Questions

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References