Wasmannia williamsoni

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Central-eastern Argentina (La Pampa, Buenos Aires provinces) and southern Brazil (Santa Catarina, Rio Grande do Sul). Found under stones in arid shrublands, grasslands, and caldenal forest districts, often at 400-1000m elevation in mountain grasslands ^[2][3][4].
• Colony Type: Likely monogyne, small colonies with a single queen found under stones ^[2].
• Size & Growth:
  • Queen: Size data unavailable, no total length published ^[2].
  • Worker: Size data unavailable, workers are the largest in the genus but no total length recorded ^[1].
  • Colony: Small, field observations suggest under 100 workers ^[2].
  • Growth: Moderate (inferred from related Wasmannia species).
  • Development: Not documented, estimate based on typical Myrmicinae: roughly 6-10 weeks at optimal temperature. (Development likely depends on temperature, keep at 20-25°C for steady growth.)
• Antkeeping:
  • Temperature: Keep at 20-25°C for activity and brood development. They experience summer means of 20.5°C and winter means of 8°C, with absolute highs up to 40°C and frequent winter frosts ^[2]. Avoid temperatures below 5°C or above 35°C.
  • Humidity: Moderate, natural rainfall is 500-800mm/year ^[2]. Keep nest substrate moderately moist but not waterlogged. Provide a water source.
  • Diapause: Yes, likely required, natural winters are cold (mean 8°C, frosts common). Provide 2-3 months at 10-15°C during winter ^[2].
  • Nesting: Ground-nesting under stones in arid grasslands ^[2]. Use test tubes for founding, for larger colonies, use a naturalistic setup with soil and flat stones, or Y-tong (AAC) nests with tight chambers.
• Behavior: Generally calm and non-aggressive. Workers are small and active foragers, likely feeding on small invertebrates and honeydew ^[2]. Escape risk is high due to tiny size, use standard barrier methods (fluon or talc). They prefer tight spaces and avoid open areas.
• Common Issues: slow colony growth due to small colony size, beginners may lose patience., cold sensitivity, sudden drops can stress colonies, maintain stable temperatures., high escape risk from tiny workers, seal all gaps in the setup., humidity management, avoid both drying out and waterlogging., winter diapause is likely needed for colony health, provide a cool rest period.

Housing and Nest Setup

Wasmannia williamsoni naturally nests under stones in arid shrublands and grasslands ^[2]. For captive care, a test tube with a water reservoir and cotton plug works well for founding. For established colonies, use a naturalistic setup with a soil substrate and flat stones on top, or a Y-tong (AAC) nest with small chambers. Because workers are tiny, ensure all gaps are sealed with fluon or similar barriers to prevent escape. Keep the nest area dark and stable.

Feeding and Diet

As a member of the tribe Attini, this species likely feeds on small insects, honeydew, and possibly seeds, though specific dietary studies are lacking ^[2]. Offer small live prey like fruit flies, pinhead crickets, or tiny mealworms. Provide sugar water or honey for carbohydrates. Feed protein 2-3 times per week and remove uneaten prey after 24 hours to prevent mold.

Temperature and Seasonal Care

This species comes from temperate regions with distinct seasons ^[2]. Summer averages 20.5°C, winter 8°C, with frequent frosts. Keep colonies at 20-25°C for optimal activity. During winter, provide a diapause period of 2-3 months at 10-15°C to mimic natural conditions, this is likely important for colony health. Avoid temperatures below 5°C or above 35°C.

Humidity and Water Needs

Natural rainfall is 500-800mm/year, moderate ^[2]. Keep the nest substrate moderately moist, damp but not waterlogged. A test tube setup with a water reservoir maintains good humidity. For naturalistic setups, mist the soil occasionally and let it partially dry between waterings. Provide a separate water tube or dish.

Colony Structure and Growth

Wasmannia williamsoni forms small colonies with a single queen (monogyne, inferred from field observations) ^[2]. Field collections found only dozens of workers, and males have never been recorded. The queen is dark brown, slightly larger than workers. Growth is moderate, expect several months for first nanitics, and potentially over a year to reach a modest colony size. Colonies likely peak in summer.

Frequently Asked Questions

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References