Strumigenys osellai

Quick Summary

• Difficulty: Hard
• Origin & Habitat: Ecuador, Pichincha province, Nanegalito (0°03′ N, 78°41′ W),1560 m elevation, cloud forest ^[1]
• Colony Type: Unknown, only a worker and a queen have ever been described ^[1]
• Size & Growth:
  • Queen: 2.8 mm ^[1]
  • Worker: 2.5 mm ^[1]
  • Colony: Unknown, no colony data exist. Related species typically have small colonies (under 100 workers).
  • Growth: Unknown
  • Development: Unknown, no captive or wild data available (Based on similar Strumigenys, development may take several months, but this is unconfirmed.)
• Antkeeping:
  • Temperature: Cool to moderate, cloud forest at 1560 m suggests 18-22 °C. Start in the low 20s and watch the colony, adjust if they avoid or crowd the heat source.
  • Humidity: High, cloud forest origin means consistently damp substrate. Keep the nest material moist but not waterlogged. Provide a gradient with a drier area so the ants can choose.
  • Diapause: Unknown, given the tropical origin, a true diapause is unlikely, but activity may drop during cooler periods. No specific data.
  • Nesting: Nests naturally in soil ^[1]. In captivity, use a plaster or Y‑tong nest with small, tight chambers to match their tiny size. A naturalistic soil setup also works.
• Behavior: Predatory, they hunt small invertebrates with their long mandibles. Likely shy and non‑aggressive, they avoid confrontation. Their tiny size (under 3 mm) makes escape a constant risk, use fine mesh and seal all gaps. Workers forage alone, not in groups.
• Common Issues: tiny size makes escape easy without ultra‑fine mesh barriers, no captive breeding data, establishing a colony is experimental, high humidity can lead to mold if ventilation is poor, predatory diet can be hard to sustain, need a steady supply of live springtails or similar micro‑prey, almost never available in the hobby

Origin and Natural Habitat

Strumigenys osellai comes from the cloud forests of Ecuador, found only at Nanegalito in Pichincha province,1560 m elevation ^[1]. Cloud forests are misty, humid, and cool. The type specimens were sifted from soil on the forest floor, so these ants nest in the ground among leaf litter and organic matter ^[1].

The species was described in 2008 by Rigato and Scupola, making it a relatively new addition to ant science ^[1]. It belongs to the gundlachi‑complex of the Strumigenys gundlachi‑group, characterized by long mandibles, long trigger hairs, and two small intercalary denticles between the apical teeth ^[1]. The species name honors Professor Giuseppe Osella, one of the collectors ^[1].

Size and Appearance

This is a very small ant, workers are 2.5 mm long and queens 2.8 mm ^[1]. The mandibles are long and narrow, with multiple teeth: 7 on the left mandible and 5 on the right in workers, and 5/6 in queens ^[1]. The body is brown, mandibles, antennae, and tarsi are light testaceous, while the legs are light brown ^[1].

The postpetiole is noticeably wider than the petiole, and the gaster has a thin spongiform lamella at the front ^[1]. These details are best seen under magnification, the ants are too small for the naked eye to make out much detail.

Temperature and Heating

Based on their cloud forest home at 1560 m, these ants probably prefer cool‑to‑moderate temperatures, likely 18-22 °C ^[1]. Start around 20 °C and watch the colony. If they become sluggish, warm things up a bit, if they avoid the heated area, cool it down.

Use a heating cable on one side of the nest to create a temperature gradient. Always place the heating element on top of the nest, not underneath, to avoid drying out the substrate too quickly.

Humidity and Moisture

Coming from a cloud forest, Strumigenys osellai needs high humidity. Keep the nest substrate consistently damp, it should feel moist to the touch, but not waterlogged. In nature they experience constant mist and high ambient humidity.

In captivity, moisten the substrate regularly and use a lid that retains some moisture while still allowing air exchange. Aim for a balance: too much airflow dries things out, too little causes mold. A small water reservoir connected to the nest can help maintain stable humidity.

Feeding and Diet

Strumigenys are predators. They hunt tiny invertebrates like springtails, mites, and small fly larvae. For Strumigenys osellai, offer live springtails as the main food, they are the right size for these 2.5 mm workers.

Do not count on sugar‑water or honey, while some Strumigenys may occasionally take them, they are not a reliable food source. Provide live prey 2-3 times per week, and remove any uneaten prey after 24 hours to prevent mold.

Nesting Setup

In the wild they nest in soil ^[1]. For captivity, use a plaster or Y‑tong nest with very small, low chambers that match the ants’ tiny size. A naturalistic set‑up with moist soil also works well. Avoid tall open spaces, these ants prefer tight, enclosed crevices.

They are not strong excavators, so pre‑formed chambers are better than loose substrate. The nest material should hold moisture without becoming waterlogged. Cover the nest with a dark panel to give them security.

Behavior and Temperament

Strumigenys osellai is likely shy and non‑aggressive, preferring to hide rather than fight. Workers hunt alone, not in groups. Their long mandibles are used to catch tiny prey, not for defense.

They can sting (typical of myrmicine ants), but it is not medically significant and they are far too small to sting a human effectively. Their main defense is escape. Because of their tiny size, you must use very fine mesh (e.g.,0.1 mm) on ventilation holes and seal all cracks, they can squeeze through gaps you might not even see.

Frequently Asked Questions

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References