Solenopsis wasmannii

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Native to Argentina, Bolivia, Brazil, Chile, and Paraguay. It inhabits tropical dry forests, cerrado (savanna), and Atlantic Forest remnants at elevations from 450 m to 1400 m ^[1]. It has been recorded in semi-deciduous forests, eucalyptus plantations, and disturbed areas ^[3][4][5].
• Colony Type: Unknown, no specific data on queen number. Based on typical Solenopsis patterns, likely monogyne (single queen), but unconfirmed.
• Size & Growth:
  • Queen: 6-9 mm ^[1]
  • Worker: 1.80-5.28 mm (polymorphic) ^[1]
  • Colony: Unknown, related Solenopsis can reach several thousand workers, but no direct data for S. wasmannii
  • Growth: Unknown, inferred moderate at tropical temperatures
  • Development: Estimated 4-6 weeks at 25-28°C (based on related tropical Solenopsis, no specific data) (Development time is temperature-dependent, keep warm for best growth)
• Antkeeping:
  • Temperature: Keep at 24-28°C. These are tropical ants and need consistent warmth. A heating cable on one side of the nest creates a gradient ^[1]. Avoid prolonged temperatures below 20°C.
  • Humidity: Provide a gradient: keep the nest substrate slightly moist in one area and dry in another. This species naturally inhabits seasonally dry forests, so it can tolerate some drying, but avoid total desiccation.
  • Diapause: No, as a tropical species, it does not require winter hibernation. Maintain stable warmth year-round.
  • Nesting: Ground-nesting, naturally under stones and in soil. In captivity use a Y-tong (AAC), plaster, or soil nest with a hydration chamber. A test tube setup works for founding colonies.
• Behavior: A thief ant, opportunistic forager that scavenges and may steal food from other colonies. Workers are generally non-aggressive toward keepers but will defend their nest. They have a functional stinger (Myrmicinae, Solenopsidini) armed with piperidine alkaloid venom. The sting is mild and not dangerous. Minors are very small (1.8 mm), so escape prevention is critical, use fluon or PTFE on nest edges and seal gaps. Activity pattern unknown, likely both day and night.
• Common Issues: tropical temperature requirements, colonies can decline if kept below 20°C for long, escape risk, tiny minor workers fit through very small gaps, secure all openings, mold from overhumidification, provide a humidity gradient to avoid constant wetness, fragile founding stage, queens need stable conditions and minimal disturbance

Housing and Nest Setup

Solenopsis wasmannii naturally nests under stones and in soil cavities in forests and savannas ^[1]. In captivity, you can use a Y-tong (AAC) nest, a plaster nest, or a naturalistic soil setup. Because the colony contains both tiny minors (around 1.8 mm) and majors over 5 mm, include chambers of varying sizes, some narrow for minors and wider for majors. Provide a hydration system in one section to create moisture, leaving other sections dry. A test tube attached to a small outworld works well for founding colonies. As the colony grows, transfer them to a larger formicarium before they outgrow the tube. Always use escape prevention on the outworld edges.

Feeding and Diet

These ants are opportunistic feeders (thief ants). In captivity, offer protein sources such as small insects (fruit flies, pinhead crickets, mealworms) and sugar sources like honey water or sugar water. They may also scavenge dead insects. Feed protein 2-3 times per week and maintain a constant supply of sugar water. Remove uneaten prey after 24-48 hours to prevent mold. They are adaptable and will accept a variety of foods. ^[1]

Temperature and Seasonal Care

As a tropical species from warm South American habitats, keep the temperature between 24-28°C. Avoid prolonged exposure below 20°C, which can slow development or harm the colony. Use a heating cable on one side of the nest to create a gradient, this allows the ants to choose their preferred temperature. Place the heating on top of the nest (not underneath) to prevent excessive drying. No hibernation is needed, maintain stable warmth year-round. A simple thermometer near the nest helps monitor conditions ^[1].

Colony Development and Growth

How colonies start is unconfirmed, but based on related Solenopsis, the queen likely raises the first brood without foraging (claustral founding). At optimal temperatures (24-28°C), the first tiny workers (nanitics) should appear in about 4-6 weeks. As the colony grows, you will see increasing size variation, minor workers are small (1.8 mm) while majors can exceed 5 mm with enlarged heads ^[2]. Colony size in the wild is unknown, but mature colonies might reach several hundred to a few thousand workers based on related species. Development is steady with warm temperatures, do not disturb the queen during founding.

Behavior and Temperament

Solenopsis wasmannii is generally calm and not aggressive toward keepers. As a thief ant, it avoids confrontation and focuses on scavenging and stealing food from other colonies. When threatened, workers will sting, they belong to the Myrmicinae subfamily (tribe Solenopsidini) and inject a venom composed of piperidine alkaloids. The sting is mild and not a concern for healthy humans. The smallest workers can squeeze through tiny gaps, so sealing the formicarium thoroughly is essential. Use fluon or PTFE on the inner walls of the outworld. Activity patterns are undocumented, assume they may forage both day and night.

Frequently Asked Questions

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References