Pseudomyrmex longus

Pseudomyrmex longus

Pseudomyrmex longus is a small, slender ant species native to the southern Neotropics, found across Argentina, Brazil, Paraguay, and into Colombia ^[1]. Workers measure approximately 0.86-1.05mm in head width, making them one of the smaller species within the genus ^[2]. They have relatively short eyes compared to other Pseudomyrmex species, with an eye length ratio of 0.47-0.51 ^[2]. These ants are ground-nesting, found exclusively in the shallow subsurface layer (0-10cm depth) in their native range ^[3].

As with other Pseudomyrmex species, P. longus likely exhibits the characteristic slender, elongated body form that gives the genus its common name of "twig ants." They are probably predatory or omnivorous, hunting small invertebrates and tending honeydew-producing insects. Their small size and ground-nesting habits distinguish them from many arboreal Pseudomyrmex species.

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Native to the southern Neotropical region, Argentina, Brazil, Paraguay, and Colombia ^[1]. Found in the subtropical landscapes of Paraná, Brazil, where they inhabit the shallow subsurface layer (0-10cm depth) ^[3]. Also recorded in Colombia's western regions (Cauca, Risaralda, Valle del Cauca) ^[4][2].
• Colony Type: Colony structure is unconfirmed. Based on typical Pseudomyrmex patterns, likely single-queen colonies with moderate worker numbers.
• Size & Growth:
  • Queen: Estimated 5-7mm based on genus patterns
  • Worker: 0.86-1.05mm head width ^[2]
  • Colony: Likely small to moderate (100-500 workers) based on genus patterns
  • Growth: Moderate, estimated based on related species
  • Development: Estimated 6-10 weeks at optimal temperature based on typical Pseudomyrmex development (Development time is estimated from genus-level data since species-specific studies are unavailable)
• Antkeeping:
  • Temperature: Keep at 22-26°C. These are subtropical ants that tolerate moderate warmth. A heating cable on one side of the nest creates a suitable gradient.
  • Humidity: Maintain moderate to high humidity. Keep the nest substrate consistently moist but not waterlogged. These ants live in shallow ground layers where moisture is typically stable.
  • Diapause: Unknown, subtropical species may have reduced activity in cooler months but true hibernation is unlikely
  • Nesting: Natural nesting occurs in shallow subsurface soil and likely small cavities in dead wood or twigs. In captivity, a Y-tong nest or plaster nest with tight chambers works well. Avoid large, open spaces, scale chambers to their tiny size.
• Behavior: Likely aggressive for their small size, as typical for Pseudomyrmex. They are probably active foragers and may be predatory on small invertebrates. Escape prevention is critical due to their tiny size, use fine mesh and tight-fitting barriers. Workers are fast-moving and may be defensive.
• Common Issues: escape prevention is critical due to their very small size, they can squeeze through standard barrier gaps, small colony size means losses have bigger impact, avoid disturbing founding colonies, humidity management is important, they may be sensitive to drying out, limited availability in the antkeeping hobby means established colonies are rare

Nest Preferences and Housing

Pseudomyrmex longus naturally nests in shallow subsurface soil and small cavities in dead wood or twigs at depths of 0-10cm ^[3]. In captivity, provide a nest that mimics these conditions. A Y-tong (acrylic) nest with small, tight chambers works well for their tiny size. Plaster nests also maintain humidity well. Avoid large, open chambers, these ants feel safer in snug spaces scaled to their body size. The nest should have a water reservoir or moisture chamber to maintain consistent humidity. Since they are ground-nesting, provide a shallow outworld with soil or a soil chamber for foraging.

Feeding and Diet

Like other Pseudomyrmex species, P. longus is likely omnivorous with predatory tendencies. They probably hunt small invertebrates (springtails, booklice, fruit flies) and also consume honeydew from aphids or scale insects. In captivity, offer small live prey items like fruit flies, pinhead crickets, and small mealworms. Sugar sources like honey water or sugar water may be accepted, though some Pseudomyrmex species prefer protein over sweets. Feed protein prey 2-3 times per week and provide a constant sugar source. Remove uneaten prey promptly to prevent mold.

Temperature and Seasonal Care

Maintain temperatures between 22-26°C. These subtropical ants from southern South America prefer warm conditions but not extreme heat. A heating cable placed on one side of the nest creates a thermal gradient allowing ants to regulate their temperature. Room temperature within this range is usually sufficient. During cooler months, reduce feeding frequency slightly but no true hibernation is expected. If colony activity decreases in winter, simply reduce temperatures slightly (by 2-3°C) rather than attempting full hibernation.

Behavior and Temperament

Pseudomyrmex ants are known for being aggressive and defensive, even from small colonies. Workers are fast-moving and will readily defend the nest against threats. Their small size makes them excellent escape artists, use fine mesh (at least 0.5mm or smaller) on all openings and apply fluon or other barriers to prevent escapes. When working with the colony, move slowly and avoid sudden vibrations. They are likely diurnal foragers, actively searching for food during daylight hours. A well-designed outworld with multiple feeding stations helps prevent resource competition.

Colony Establishment and Growth

Established colonies may be difficult to find in the antkeeping hobby due to their limited distribution and small colony sizes. If acquiring a queen, she will likely seal herself in a claustral chamber and raise the first brood alone, as typical for Pseudomyrmex. The founding stage takes several months, with first workers (nanitics) being smaller than mature workers. Growth is moderate, expect 6-10 weeks from egg to first worker at optimal temperature. Once established, colonies grow steadily but remain smaller than many common ant species. Patience is key during the founding phase.

Frequently Asked Questions

References