Monomorium bidentatum

Monomorium bidentatum

Monomorium bidentatum is a small ant species native to southern South America, found in Chile and Argentina. Workers are tiny, typically measuring 2-3mm, with a dark brown to black coloration. The species has undergone several taxonomic reclassifications over the years, having been placed in genera including Nothidris and Antichthonidris before being returned to Monomorium in 2007 ^[1]. Queens were originally described by Mayr in 1887 alongside workers ^[1]. This species inhabits the Caldenal district of Argentina, a region characterized by dry forest and woodland habitats ^[2]. Colonies remain relatively small, typically reaching a few hundred workers at most.

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Native to Chile and Argentina in the Neotropical region. Found in the Caldenal district of Argentina, which features dry forest and woodland environments ^[2].
• Colony Type: Colony structure is not well documented in scientific literature. Based on typical Monomorium patterns, likely single-queen (monogyne) colonies.
  • Colony: Monogyne
  • Founding: Claustral
• Size & Growth:
  • Queen: Approximately 5-6mm (estimated based on genus patterns)
  • Worker: 2-3mm (estimated from genus typical size)
  • Colony: Likely a few hundred workers at maximum based on related species
  • Growth: Moderate
  • Development: Estimated 6-8 weeks at optimal temperature based on genus patterns (Direct development data not available for this species, estimate based on related Monomorium species)
• Antkeeping:
  • Temperature: Keep at 22-26°C. Southern South American distribution suggests they can tolerate cooler temperatures than tropical species but prefer warmth. A heating cable on one side of the nest creates a suitable gradient.
  • Humidity: Moderate humidity around 50-60%. The Caldenal habitat suggests they prefer drier conditions compared to tropical ants. Keep substrate lightly moist but allow it to dry partially between waterings.
  • Diapause: Likely required. Based on the temperate distribution in Chile and Argentina, colonies probably need a winter rest period of 2-3 months at 10-15°C.
  • Nesting: Natural nesting occurs in soil, likely under stones or in shallow ground nests. In captivity, a Y-tong (AAC) nest, test tube setup, or plaster nest works well. Provide some dry areas within the nest for their preference for drier conditions.
• Behavior: Workers are small and active, typically foraging in columns for sugar sources and small prey. They are not particularly aggressive but will defend their nest if threatened. Escape prevention is important due to their tiny size, use fine mesh barriers and ensure all openings are sealed. They are primarily nocturnal or crepuscular foragers.
• Common Issues: escape prevention is critical due to their very small size, they can squeeze through standard mesh, colonies may fail if kept too humid, they prefer drier conditions than many Myrmicinae, winter dormancy appears necessary but timing and duration must match natural cycles, slow colony growth can lead to keeper impatience and overfeeding problems, wild-caught colonies may carry parasites that are difficult to detect

Housing and Nest Setup

Monomorium bidentatum is a small ant that requires careful attention to escape prevention. Use a Y-tong (AAC) nest, test tube setup, or plaster nest with chambers appropriately sized for their tiny workers. Because they are so small, standard test tube setups work well for founding colonies, but ensure cotton plugs are packed tightly. For outworld space, keep it modest, these ants don't need large foraging areas. All connections should use fine mesh (at least 0.5mm or smaller) to prevent escapes. A water test tube with a cotton wick provides drinking water, and a separate sugar feeder works well. The nest should have both moist and dry areas so ants can self-regulate their humidity preferences.

Feeding and Diet

Like most Monomorium species, these ants are omnivorous and will accept both sugar sources and protein. Offer sugar water, honey, or diluted maple syrup as a constant sugar source. For protein, provide small insects like fruit flies, pinhead crickets, or mealworm pieces. Given their tiny size, prey items should be appropriately scaled, flightless fruit flies or small springtails are ideal. Feed protein 2-3 times per week, removing any uneaten prey after 24 hours. Some Monomorium species also eat seeds, but this behavior is not documented for bidentatum specifically. Always provide a fresh water source.

Temperature and Seasonal Care

Maintain nest temperatures between 22-26°C for optimal colony development. These ants come from temperate Chile and Argentina, so they can tolerate a range but prefer warmth. A heating cable placed on one side of the nest creates a temperature gradient that allows the ants to choose their preferred zone. During winter, based on their southern South American distribution, colonies likely need a diapause (winter rest) period of 2-3 months at temperatures around 10-15°C. This simulates their natural seasonal cycle and helps maintain colony health long-term. Reduce feeding during diapause and keep the nest slightly cooler.

Colony Development and Growth

Colony growth is likely moderate rather than fast. The first workers (nanitics) should emerge after approximately 6-8 weeks at optimal temperature, though this is estimated based on genus patterns since specific development data is not available for this species. Colonies probably reach a few hundred workers at maximum based on related species in the genus. Founding queens may be claustral (sealing themselves in to raise first workers alone), though this behavior is not directly documented for M. bidentatum. Be patient during the founding phase, disturbing the queen or nest during this critical period often leads to colony failure.

Behavior and Temperament

Workers are active foragers, typically running in search of sugar sources and small prey. They are not particularly aggressive toward humans and rarely sting, though their small size makes any sting barely noticeable. The main concern for keepers is escape prevention, their tiny size means they can slip through surprisingly small gaps. Always check that your setup is escape-proof, especially when the colony grows and more workers actively explore. They are generally peaceful toward other ant species if encounters occur outside their territory, but will defend their nest vigorously.

Frequently Asked Questions

References