Nesomyrmex mirassolis

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Southeastern Brazil, specifically São Paulo state (Mirassol and Agudos regions). Natural habitat is tropical to subtropical forest. Nesting documented in hollow stems of Piper aduncum ^[1].
• Colony Type: Unconfirmed. Only single specimens have been documented, it is unknown if colonies are monogyne (single queen) or polygyne (multiple queens). No data on ergatoid queens.
• Size & Growth:
  • Queen: size data unavailable
  • Worker: size data unavailable
  • Colony: Unknown, only single specimens collected, no colony data exists
  • Growth: Unknown
  • Development: No data available for this species (Development time is unconfirmed. Any estimates would be pure speculation.)
• Antkeeping:
  • Temperature: No specific data, as a tropical Brazilian species, keep warm (likely 22-26°C) and stable. Avoid prolonged cold.
  • Humidity: No specific data, inferred from stem‑nesting habit, keep nest substrate consistently moist but not waterlogged. High humidity is likely essential.
  • Diapause: Unknown, tropical species likely do not require true hibernation, but no evidence exists.
  • Nesting: In the wild they nest in hollow plant stems ^[1]. In captivity, use small, enclosed spaces, test tubes, small Y‑tong (AAC) nests, or plaster nests with narrow chambers scaled to their tiny size. Avoid open, large chambers.
• Behavior: Non‑aggressive and shy. Workers are small and tend to stay hidden. They belong to the Crematogastrini tribe and use a smear‑type venom, they have a modified, flattened stinger that wipes venom onto threats rather than piercing, so they are harmless to humans. Escape risk is moderate due to tiny size, fine mesh or tight seals are needed. Foraging likely quiet and limited.
• Common Issues: extremely rare in the hobby, almost impossible to obtain legally, no established captive breeding lines, wild collection is the only option but damaging to wild populations, high humidity required, colonies will fail quickly if nest dries out, tiny size makes escape easy, sealing every gap is critical, no species‑specific care data exists, keepers must experiment blindly

Housing and Nest Setup

Nesomyrmex mirassolis is best kept in small, enclosed nests that mimic its natural hollow‑stem home. Test tubes with a water reservoir at one end work well for small colonies. For larger groups, choose small Y‑tong (AAC) or plaster nests with narrow chambers. Because these ants are tiny, every connection between nest and outworld must be tightly sealed, use fine mesh (e.g.,0.1 mm) or petroleum jelly barriers to prevent escape. Avoid large, open spaces, they seem to prefer cozy, cluttered chambers. The only nest site reported in nature is a hollow stem ^[1].

Feeding and Diet

No dietary data exists for this species. Based on typical Nesomyrmex, offer a standard ant diet: constant access to sugar water (1:1 dilution) or honey, and protein from small insects like fruit flies, pinhead crickets, or crushed mealworms. Feed protein 2-3 times per week and remove uneaten prey after 24 hours to avoid mold. Because workers are tiny, prey should be very small or crushed. Adjust based on colony acceptance.

Temperature and Humidity

70% RH) conditions. Keep the nest substrate moist (but not waterlogged) by adding water to the test tube reservoir or misting the nest lightly. Good ventilation is important to prevent mold. If ants cluster near the water source or appear sluggish, humidity may be too low.

Colony Establishment

Establishing a captive colony is extremely difficult because of the species’ rarity and the complete lack of care data. If you obtain a mated queen, house her in a test tube setup in a dark, undisturbed place. Do not disturb her until the first workers appear, any handling could cause stress and failure. There is no information on founding method, all speculation about claustral or semi‑claustral is unfounded. Observe the queen but do not open the nest unless absolutely necessary. Once workers emerge (timing unknown), offer very small amounts of sugar water and tiny prey. The first workers may be smaller than average. Move to a larger nest only when the colony clearly outgrows the test tube.

Behavior and Temperament

Nesomyrmex mirassolis is calm and non‑aggressive. It belongs to the Crematogastrini tribe, which uses a modified, spatulate stinger to smear venom onto threats rather than piercing. It is harmless to humans, the venom is applied topically and is not a sting. Workers are small and tend to stay hidden, they are not quick to forage or defend. This makes them low‑stress to observe, but also easy to lose if boundaries aren’t secure. Escape risk is moderate due to their tiny size: fine mesh or tight seals are essential.

Frequently Asked Questions

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References