Solenopsis westwoodi

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Argentina, Paraguay, and southern Brazil. In the wild, these ants are typically found nesting in association with leafcutter ants (Atta and Acromyrmex) in the Buenos Aires region and surrounding areas ^[1]. They prefer warm, humid Neotropical environments.
• Colony Type: Colony structure is not documented in scientific literature. Keepers should assume single-queen colonies until proven otherwise, but this is unconfirmed.
• Size & Growth:
  • Queen: ~4 mm (total length) ^[1]
  • Worker: 1.44-1.56 mm (total length) ^[1]
  • Colony: Unknown, likely small to moderate (under 500 workers) based on related thief ants, but specific data is unavailable.
  • Growth: Moderate, based on typical Solenopsis development patterns.
  • Development: Estimated 6-10 weeks at optimal temperatures (based on related Solenopsis species), specific data for S. westwoodi is not available. (Development time is unconfirmed for this species. Keep conditions stable and observe.)
• Antkeeping:
  • Temperature: Keep at 24-28°C. These are Neotropical ants that prefer warm conditions. A heating cable on one side of the nest can create a suitable gradient.
  • Humidity: High humidity is essential, keep the nest substrate consistently moist but not waterlogged. A water reservoir or test tube setup works well. Avoid letting condensation pool.
  • Diapause: Not required. As a Neotropical species from Argentina, Brazil, and Paraguay, they do not experience harsh winters and do not need a diapause period.
  • Nesting: Y-tong (AAC) nests, plaster nests, or test tube setups work well for these small ants. They prefer tight, humid chambers. Given their association with leafcutter ants in the wild, they may benefit from a naturalistic setup with multiple connected chambers, but open spaces should be avoided.
• Behavior: These are shy, secretive ants that prefer to stay hidden. Workers are tiny (under 2 mm) and very quick-moving. They have a sting (typical for Solenopsidini) but are not aggressive and will flee rather than fight. Their main defense is escaping and hiding. Escape prevention is critical due to their tiny size, they can slip through standard barriers. They are primarily nocturnal and will establish foraging trails to nearby food sources.
• Common Issues: escape prevention is critical due to their tiny 1.5 mm worker size, use fine mesh, fluon barriers, and tight-fitting lids, colonies may be difficult to establish from queen alone because founding behavior is unconfirmed, queens likely need dark, undisturbed conditions, high humidity requirements can lead to mold if ventilation is poor, ensure airflow while maintaining humidity, their kleptoparasitic nature may make them shy about foraging in open spaces, offer food near nest entrances and provide cover, their small size makes them vulnerable to drowning in open water sources, use cotton-plugged test tubes or sponges

Housing and Nest Setup

Use small, tight enclosures due to the tiny worker size (1.44-1.56 mm). A Y-tong (AAC) formicarium with narrow chambers works well, tight spaces mimic their natural nesting near host ant colonies. Alternatively, a well-humidified test tube setup works for founding colonies. Provide a humidity gradient by placing a water reservoir on one end of the nest. Avoid large open areas, these shy ants will avoid exposed spaces and may not forage properly. Escape prevention is critical: use fluon barriers on all surfaces and seal every connection, these ants can slip through gaps that would stop larger ants ^[1].

Feeding and Diet

Solenopsis westwoodi is a thief ant that specializes in stealing food from other ant colonies, particularly leafcutter ants like Atta and Acromyrmex, in whose nests they have been found ^[1]. In captivity, offer small protein sources such as fruit flies, pinhead crickets, or tiny mealworm pieces. They also accept sugar water or honey. Because of their tiny size, food must be appropriately sized, even a small mealworm piece may be too large. Feed small amounts every 2-3 days and remove leftovers within 24 hours to prevent mold. Their feeding behavior is secretive, place food near nest entrances and provide dark covers to encourage foraging.

Temperature and Humidity

These Neotropical ants need warm, humid conditions. Keep the nest area at 24-28°C. Use a heating cable on one side of the nest to create a gentle gradient if your room is cooler. Place the heating on top of the nest, not underneath, to avoid drying out the substrate too quickly. Humidity should be high, keep the substrate consistently moist but not waterlogged. Use a cotton-plugged test tube with a water section or a connected water reservoir. Mist the nest occasionally, but avoid condensation that can drown small ants. Good ventilation is essential to prevent mold while maintaining humidity, small holes or mesh panels work well.

Colony Development

Queens measure about 4 mm and are golden brown with yellowish appendages ^[1]. Founding behavior is unconfirmed, it is not known whether queens are claustral or semi-claustral. Keepers should provide a small, dark, sealed chamber for the queen and disturb her as little as possible during founding. Do not offer food until workers appear, as she may be sealed away. After the first workers (nanitics) emerge, colony growth is likely moderate, with several hundred workers at maturity. Be patient, the founding stage can be slow ^[1].

Behavior and Temperament

These are shy, non-aggressive ants. They have a sting (typical of Solenopsidini) but are unlikely to use it on humans, they prefer to flee and hide. Workers are fast-moving and will retreat if disturbed. They are primarily nocturnal, so most activity will be in the evening. Their kleptoparasitic nature means they may establish hidden foraging trails and investigate other ant colonies if present. Their tiny size demands excellent escape prevention, they can squeeze through remarkably small gaps. Provide plenty of dark, covered spaces in the nest to make them feel secure ^[1].

Frequently Asked Questions

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References