Tetramorium robertsoni

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Tanzania, East Africa, found in savanna habitats, for example on unburnt slopes in Mkomazi Game Reserve and near Amani ^[1][2]
• Colony Type: Unconfirmed, likely monogyne (single queen) based on typical Tetramorium patterns, but no species‑specific data exists
• Size & Growth:
  • Queen: Unknown, not described in the literature, estimated ~6‑8mm from genus patterns
  • Worker: Size data unavailable (only head and other partial measurements exist), estimated ~3‑4mm based on typical Tetramorium worker size
  • Colony: Unknown, typical Tetramorium reach several hundred workers
  • Growth: Moderate, estimated from genus patterns
  • Development: Estimated 6‑8 weeks at 24‑26°C based on related Tetramorium species (Development timeline is unconfirmed for this species, estimates are based on genus‑level data for savanna Tetramorium)
• Antkeeping:
  • Temperature: Keep at 22‑26°C. These are African savanna ants that need stable warmth. A heating cable on one side of the nest creates a useful temperature gradient.
  • Humidity: Moderate, keep the nest substrate slightly moist but allow parts to dry. Savannah species tolerate drier conditions than forest ants.
  • Diapause: Unlikely, Tanzania is near the equator with little seasonal temperature change. A slight winter temperature drop is fine but not needed.
  • Nesting: In nature they likely nest in soil under stones or shallow cavities. In captivity a Y‑tong (AAC) or plaster nest works well. Provide a moisture gradient so the colony can choose its preferred humidity.
• Behavior: Typical of Tetramorium, generally non‑aggressive but will defend the nest. Workers forage for small insects and honeydew. As Myrmicinae they possess a functional stinger and can deliver a mild sting if handled roughly. Escape risk is moderate: these ants are small but not as prone to escaping as tiny species like Pheidole.
• Common Issues: very little biological data exists, making care recommendations uncertain, wild‑caught colonies may carry parasites that are hard to treat, colony growth may be slow due to limited founding documentation, temperature management is critical, avoid cold drafts, small colonies need careful feeding to avoid mold from excess food

Appearance and Identification

Tetramorium robertsoni workers are small ants, estimated at roughly 3‑4mm total length. They are uniformly brown with lighter legs and antennae. Their head is slightly longer than wide, and they have relatively large eyes for a Tetramorium, probably an adaptation for open savanna. They are covered with many long, simple, standing hairs on the head, middle body, petiole, postpetiole, and gaster. Other key features: long propodeal spines, a high nodiform petiole, and an unsculptured, shiny clypeus (the front part of the head above the mandibles) ^[1]. These traits separate them from similar species like Tetramorium edouardi and Tetramorium rubrum ^[1].

Natural History and Distribution

This species is known only from a few locations in Tanzania, East Africa. Type specimens were collected in savanna habitats of the Mkomazi Game Reserve (on an unburnt slope) and near Amani in the Eastern Arc Mountains ^[1]. Unlike some Tetramorium that prefer forest understory, T. robertsoni shows a clear preference for open areas ^[2]. The savanna environment gives them warm temperatures year‑round with distinct wet and dry seasons, not cold winters ^[1].

Housing and Nest Setup

For Tetramorium robertsoni, a Y‑tong (AAC) or plaster formicarium works well. These ants appreciate a moisture gradient, keep one side of the nest moderately humid and the other side a bit drier, so the colony can self‑regulate. A test tube setup is fine for starting a colony, but move them to a larger nest once you have 20‑30 workers. Because they come from open savanna, make sure the outworld is well‑ventilated while the nest stays at stable humidity. Use a shallow water reservoir in the nest to provide moisture without flooding.

Feeding and Diet

Like most Tetramorium, these ants are omnivorous but prefer protein. Offer small live insects like fruit flies, pinhead crickets, or tiny mealworms. They also take sugar water or honey water. Feed protein 2‑3 times per week and remove any leftover prey after 24 hours to prevent mold. Keep a constant sugar source (a small cotton ball soaked in honey water). Since the ants are small, make sure any prey is no larger than the workers themselves.

Temperature and Seasonal Care

As savanna ants from Tanzania, Tetramorium robertsoni prefer warmth. Keep the nest at 22‑26°C. A heating cable on one side of the nest creates a temperature gradient, which many ants naturally prefer. Avoid temperatures below 20°C or above 30°C for long periods. Because Tanzania is near the equator, these ants probably do not need a true hibernation diapause. You might see less activity in winter if your room cools, but that's normal, no cold rest period is required.

Colony Development and Growth

The queen has not been described in the literature. Based on related Tetramorium, she likely measures 6‑8mm. Founding is assumed to be claustral, the queen seals herself in and raises the first brood without foraging. First workers (nanitics) will be smaller than normal workers and should appear within 6‑8 weeks at 24‑26°C. Colony growth is moderate, expect 50‑100 workers in the first year with good care. Maximum colony size is unknown but probably several hundred workers. Be patient with new colonies, they are vulnerable to stress.

Frequently Asked Questions

Report an Issue

The current care sheet is based fully on literature. See inconsistencies, or something that's incorrect? Please report here, it will be resolved after review from an admin. Contributing to the blogs tab also helps providing information, to make us be able to further improve the caresheets. Thank you for your support!

References