Scientific illustration of Tetramorium tosii ant - showing key identification features including head, thorax, and gaster.

Tetramorium tosii

Non-Parasitic Queen No Gamergate
Sci. Name
Tetramorium tosii
Tribe
Crematogastrini
Subfamily
Myrmicinae
Author
Emery, 1899
Distribution
Found in 1 countries
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Introduction

Tetramorium tosii is a relatively large and striking ant species endemic to the rainforests of Eastern and Northern Madagascar. Workers are easily recognised by their extremely long propodeal spines and long antennal scapes . The species is primarily arboreal or sub-arboreal, though it is also commonly collected on the ground . Most workers are dark brown to blackish brown, but a population from the northernmost locality at Foret de Binara is a distinct yellowish-orange to orange-brown . This colour variation, combined with the long spines, makes T. tosii one of the most visually interesting Tetramorium species from Madagascar.

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Status by country, from Kass et al. 2022 & Wong et al. 2023

Native Invasive Introduced (indoor) Intercepted Unknown
Data Sources
Year Range 2000 - 2026

Quick Summary

  • Difficulty: Medium
  • Origin & Habitat: Endemic to rainforests of Eastern and Northern Madagascar [1]. Collected at elevations from 25 m to 875 m, with highest abundance at around 425 m on the Masoala Peninsula [2][3]. The natural habitat is humid, dark, and arboreal [4].
  • Colony Type: Colony structure is unconfirmed. Based on typical Tetramorium patterns, colonies are likely monogyne (single queen).
  • Size & Growth:
    • Queen: Unconfirmed, no published queen measurements found.
    • Worker: Size data unavailable, head measurements are 0.9-1.15 mm, but total body length has not been published [1].
    • Colony: Unconfirmed, no published colony size data.
    • Growth: Moderate, estimated based on related species.
    • Development: 6-10 weeks at optimal temperature, estimated based on related Tetramorium species. (Development time is estimated as no specific data exists for this species. Their tropical origin suggests faster development than temperate species.)
  • Antkeeping:
    • Temperature: Keep at 24-28 °C, based on their tropical rainforest habitat [1][4]. Provide a slight gradient so workers can choose their preferred spot.
    • Humidity: High humidity is essential, think damp rainforest environment. Keep nest substrate consistently moist but not waterlogged [4].
    • Diapause: No, as a tropical species from Madagascar, they do not require hibernation or winter rest [1].
    • Nesting: Arboreal nature suggests they prefer nests that offer vertical space and good moisture retention. Y‑tong (AAC) or plaster nests with a water reservoir work well. They may also thrive in naturalistic setups with moist substrate and branches.
  • Behavior: A moderately active species. Workers are opportunistic feeders, foraging both on the ground and in vegetation [1]. As a member of the Myrmicinae subfamily (tribe Crematogastrini), they possess a modified stinger used for smearing venom rather than piercing, a defence mechanism known as 'smearing'. They are not particularly aggressive but will defend the nest if disturbed. Their relatively large size (for a Tetramorium) makes them easier to observe than many smaller species. Escape risk is moderate, standard barriers (e.g., fluon) are recommended.
  • Common Issues: humidity control is critical, dry conditions will stress and potentially kill colonies, as they come from humid rainforests, arboreal nature means they need vertical space and may not thrive in horizontal‑only setups, tropical species, do not hibernate or expose to temperatures below 20 °C, limited available care information makes this a species for keepers with some experience, wild‑caught colonies may have parasites or diseases from their native habitat

Housing and Nest Setup

Given their arboreal nature in Madagascar's rainforests, T. tosii needs a setup with good vertical space and excellent humidity control [1]. Y‑tong (AAC) nests or plaster nests work well because they retain moisture effectively. The nest should have a water reservoir chamber to maintain humidity over time. Provide an outworld with space for foraging, a sugar water station, and some branches or bark to mimic their arboreal environment. Since they are dark‑adapted [4], keep the nest area dimly lit. A test tube setup can work for founding colonies, but be prepared to move them to a proper formicarium once the colony grows beyond a few dozen workers.

Feeding and Diet

Like most Tetramorium species, T. tosii is an opportunistic omnivore. Offer protein sources such as small insects (fruit flies, small mealworms, crickets) two to three times per week. They will also accept sugar water or honey water, keep this available at all times. In the wild they forage both on the ground and in vegetation [1], so they likely scavenge for a variety of foods. Remove uneaten prey after 24-48 hours to prevent mold. Their relatively large size means they can tackle bigger prey than very small ant species.

Temperature and Humidity

As a tropical species from Madagascar's rainforests, T. tosii needs warm and humid conditions. Keep temperatures in the range of 24-28 °C. They are found across various elevations in the wild [2], which suggests some tolerance, but consistently warm conditions will support better colony growth. Humidity is critical, aim for 70-85% relative humidity. The nest substrate should remain consistently moist but never waterlogged. A water reservoir in the nest setup helps maintain stable humidity. Avoid temperatures below 20 °C and ensure good ventilation to prevent mold while maintaining humidity.

Colony Development

The development timeline for T. tosii is not specifically documented in scientific literature. Based on typical Tetramorium patterns and their tropical origin, expect eggs to develop into workers in approximately 6-10 weeks at optimal temperature (around 26 °C). Their relatively large worker size may indicate slightly longer development compared to smaller Tetramorium species, but this is speculative. Founding colonies may take several months to establish their first workers (nanitics). Be patient, these ants are not fast growers, but they are persistent. Once the first workers arrive, colony growth typically accelerates. [1]

Behavior and Temperament

T. tosii displays typical Tetramorium behaviour, workers are active foragers both on the ground and in vegetation, reflecting their arboreal/sub‑arboreal nature in the wild [1]. They are likely moderately defensive and will protect their nest if disturbed. As Myrmicinae (tribe Crematogastrini), they possess a functional stinger used for smearing venom rather than piercing. This defence mechanism is more about deterrence than inflicting pain. Their relatively large size makes them easier to observe than many small ant species. Workers likely communicate through chemical trails and may recruit nestmates to food discoveries, similar to other Tetramorium. Note that they are adapted to dark conditions [4], so bright light may stress them.

Frequently Asked Questions

How long does it take for Tetramorium tosii to get their first workers?

Based on typical Tetramorium development patterns, expect 6-10 weeks from egg to worker at optimal temperature (around 26 °C). Founding colonies may take 2-4 months before the first nanitics emerge. Patience is key.

Do Tetramorium tosii sting?

Yes, as a member of the subfamily Myrmicinae (tribe Crematogastrini), T. tosii has a functional stinger. However, they use it more for smearing venom than piercing, a defence mechanism typical of this tribe. They are not particularly aggressive and typically only respond when the nest is directly disturbed.

What temperature do Tetramorium tosii need?

Keep them at 24-28 °C. These are tropical rainforest ants from Madagascar, so they need warm conditions year‑round. Avoid temperatures below 20 °C.

Are Tetramorium tosii good for beginners?

This species is rated as medium difficulty. While not the most challenging ant to keep, the limited available care information and their specific humidity requirements make them better suited for keepers with some antkeeping experience. Their tropical nature means no hibernation is needed.

How big do Tetramorium tosii colonies get?

Colony size data is not published, so it is unknown. Based on typical Tetramorium patterns, expect colonies to reach several hundred workers over time, but this is speculation.

Do Tetramorium tosii need hibernation?

No. As a tropical species from Madagascar, they do not require hibernation or diapause. Keep them warm and active year‑round.

What do Tetramorium tosii eat?

They are omnivores. Offer protein sources like small insects (fruit flies, small mealworms, crickets) two to three times per week, and keep sugar water or honey water available at all times.

Can I keep Tetramorium tosii in a test tube?

Test tubes work for founding colonies, but their arboreal nature and humidity needs mean they will do better in a Y‑tong or plaster nest with a water reservoir once the colony grows beyond a few dozen workers.

Where is Tetramorium tosii found in the wild?

They are endemic to Madagascar, found primarily in the rainforests of Eastern and Northern parts of the island. They live at elevations from 25 m to 875 m and are primarily arboreal or sub‑arboreal, though often collected on the ground.

Why are my Tetramorium tosii dying?

The most likely causes are: low humidity (they need 70-85%), temperatures below 20 °C, or dry nest conditions. Check your setup and ensure the nest substrate stays moist. Also ensure good ventilation to prevent mold while maintaining humidity. Since much of the care advice is inferred, observe your colony closely and adjust conditions gradually.

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References

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This caresheet is licensed under CC BY-SA 4.0 .