Octostruma iheringi

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Neotropical lowlands from southern Mexico to southern Brazil and Jamaica. Occurs in wet to seasonally dry forests, both primary and secondary, from sea level to about 800 m elevation (with one record at 1540 m in Colombia) ^[1][3]. Lives in leaf litter and rotting wood on the forest floor.
• Colony Type: Colony structure is not documented. Dealate queens have been found together with workers in litter samples, which suggests established colonies, but the queen number is unconfirmed ^[1].
• Size & Growth:
  • Queen: Size data unavailable. Head width is 0.84 mm ^[1].
  • Worker: Size data unavailable. Head width is 0.70-0.79 mm ^[1].
  • Colony: Unknown. Based on similar leaf-litter ants, colonies are likely small (less than a few hundred workers).
  • Growth: Unknown. Likely moderate based on typical small Myrmicinae patterns.
  • Development: Unknown for this species. Related small Attini take 6-10 weeks at warm temperatures, use this as a rough estimate. (No specific development data is available. Keep conditions warm (around 24-26 °C) to encourage growth.)
• Antkeeping:
  • Temperature: Keep warm and stable, roughly 22-26 °C. As a lowland tropical species, avoid temperature extremes and sudden changes.
  • Humidity: High humidity is essential. Keep the nest substrate consistently moist but not waterlogged, feel it should be damp to the touch, with some slightly drier areas available. A soil-rotting wood mix holds moisture well.
  • Diapause: Unknown. As a tropical lowland species, diapause is probably not required, maintain consistent conditions year‑round.
  • Nesting: In nature they nest in leaf litter and rotting wood. In captivity use a naturalistic setup: moist soil mixed with small pieces of rotting wood or leaf litter. Y‑tong or plaster nests with tight, small chambers work well. Avoid large open spaces, these ants feel secure in narrow, dark cavities.
• Behavior: Shy and cryptic. They spend almost all their time hidden in the substrate. Not aggressive and not known to sting (subfamily-level sting is present but too small to bother humans). Escape prevention must be excellent, they are tiny enough to slip through very small gaps.
• Common Issues: escape through tiny gaps, use fine mesh (0.2 mm or smaller) on all openings., low humidity or sudden drying, the substrate must stay consistently moist, drying can kill the colony quickly., mold from over‑watering, ensure some ventilation and do not let water pool in the nest., stress from disturbance, they are extremely shy, minimize vibrations and light exposure., difficulty monitoring, because they hide, you may not see the colony for weeks, this is normal.

Natural History and Distribution

Octostruma iheringi is one of the most widespread species in its genus. Its range extends from southern Mexico through Central America (Guatemala, Honduras, Nicaragua, Costa Rica, Panama) into northern South America (Colombia, Ecuador, French Guiana, Venezuela, Trinidad, Paraguay) and south to Brazil ^[2][4][5]. It also occurs in Jamaica ^[1]. The species inhabits both wet evergreen forests and seasonally dry forests, from sea level to about 800 m elevation, with one Colombian record at 1540 m ^[3]. It is strictly a leaf‑litter and rotting wood specialist, almost every collection comes from sifted litter samples ^[1]. They have also been found in abandoned termite nests, suggesting they use pre‑existing cavities in decaying wood ^[6]. In surveys, they are consistently present but at low frequencies (e.g.,0.12% in central Amazonia ^[7],0.30% of specimens in a Florianópolis restinga ^[8], and 6.45% of samples in Salvador, Bahia ^[9]).

Identification and Morphology

Workers are very small, head width (HW) is 0.70-0.79 mm ^[1]. Body length (TL) has not been recorded. They are orange‑red in color, with a matte surface. The most distinctive feature is the propodeal spines: each bears a roof‑like transverse carina that makes them look like tiny horse ears ^[1]. They also have a pair of long, thin setae on the petiole, and eight erect spatulate setae on the face ^[1]. The mandibles have 8 teeth, and the antennal scrobe is deep with a translucent foliaceous rim. Queens are larger (HW 0.84 mm) with ocelli and larger compound eyes, but otherwise similar ^[1]. The species has several synonyms, Octostruma iheringi, R. simoni, R. simoni spei, R. simoni wighti, and R. sulcata, all synonymized under O. iheringi ^[5].

Housing and Nest Setup

Because Octostruma iheringi is tiny and cryptic, your setup must be scaled to their size. A test tube with a moist cotton plug can work for a small colony, but escape prevention is critical, use fine mesh (0.2 mm or smaller) around the opening. For larger colonies, use a naturalistic nest: a Y‑tong or plaster block with small, tight chambers filled with a mix of moist soil and bits of rotting wood or leaf litter. This mimics the forest floor and provides the high humidity they need. The substrate should be consistently moist but not waterlogged. Because these ants hide most of the time, you will see little activity, this is normal. A dark background and minimal disturbance will encourage them to explore slightly more.

Feeding and Diet

The natural diet of Octostruma iheringi is not documented. Based on other small leaf‑litter ants, they are probably omnivorous, taking small arthropods, honeydew, and decaying organic matter. In captivity, offer a variety of tiny live prey (fruit flies, pinhead crickets) and sugar water or honey. Because the ants are shy and may not forage in the open, place food near the nest entrance or directly into the nest using a feeding dish. Remove uneaten protein after 24 hours to prevent mold. If the colony is small, you may need to supplement with finely crushed insect powder or small pieces of boiled egg.

Temperature and Humidity

As a lowland Neotropical species, Octostruma iheringi needs warm, stable temperatures. Aim for 22-26 °C, room temperature is usually fine. Avoid letting the nest get below 18 °C or above 30 °C for extended periods. Humidity is more critical: the nest substrate must stay damp. A water reservoir connected to the nest or regular misting will help. The substrate should feel moist to the touch but not have standing water. Good ventilation is needed to prevent mold, a small mesh panel on the nest lid helps. Condensation on the walls is okay, but if water pools, reduce moisture.

Colony Establishment and Growth

Establishing a colony of Octostruma iheringi is challenging because wild‑caught colonies are rare. They are not typically found foraging in the open. If you obtain a dealate queen, founding behavior is unconfirmed, most small Myrmicinae are claustral, but this is not certain. Provide her with a small test tube setup with moist cotton and keep her in the dark and quiet. Colony growth is likely slow, the first nanitics will be extremely tiny. Be patient and avoid disturbing the colony often. Data from related species suggests 6-10 weeks from egg to first worker at 24-26 °C, but this is only a rough guide.

Frequently Asked Questions

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References