Wasmannia iheringi

Wasmannia iheringi

Wasmannia iheringi is a tiny arboreal ant species from the Neotropics, found in the rainforests of Brazil, Costa Rica, and Peru ^[1]. Workers are extremely small at only 0.5mm in head width, making them one of the smallest ants you could keep. Queens are slightly larger at 0.60-0.62mm head width ^[1]. These ants are distinctive for their specialized nesting behavior, they build small carton nests on the undersurface of leaves, creating a felt-like roof covering a portion of the leaf between veins ^[1].

What makes this species unusual is its arboreal lifestyle, unlike most ant species that nest in soil or rotting wood, W. iheringi lives entirely in the forest canopy. Colonies can have multiple queens (polygynous), with observed nests containing 27 workers,1-2 dealate queens, and males ^[1]. This is a rarely kept species that requires specialized setups mimicking their leaf-nesting behavior.

Quick Summary

• Difficulty: Hard
• Origin & Habitat: Neotropical rainforests of southeastern Brazil (Espírito Santo, São Paulo), Costa Rica, and Peru ^[1]. In Costa Rica, they inhabit the canopy of lowland rainforest on the Atlantic slope at 500-600m elevation ^[1]. Found in both Atlantic Forest and Amazon Forest regions ^[2].
• Colony Type: Polygynous colonies possible, a dense aggregation with two dealate queens has been observed ^[1]. Single-queen colonies also occur. Colonies are small, with observed nests containing around 27 workers ^[1].
  • Colony: Optionally polygyne
• Size & Growth:
  • Queen: 0.60-0.62mm head width,0.86-0.88mm mesosoma length ^[1]
  • Worker: 0.49-0.57mm head width,0.63-0.65mm mesosoma length ^[1]
  • Colony: Up to around 27 workers in observed nests ^[1]. Likely remains small, under 100 workers based on related species.
  • Growth: Unknown, likely slow given small colony size and tropical origin
  • Development: Unknown, estimate 6-10 weeks based on related Wasmannia species and tropical conditions (No direct development data available for this species. Related Wasmannia species typically develop faster in warm tropical conditions.)
• Antkeeping:
  • Temperature: Keep at 24-28°C, these are tropical rainforest ants requiring warm, stable temperatures ^[1]. Use a heating cable on one side of the nest to create a gentle gradient.
  • Humidity: High humidity required, think humid forest canopy. Keep the nest substrate consistently moist but not waterlogged. Provide a water tube for drinking access.
  • Diapause: No, these are tropical ants that do not experience cold winters. They remain active year-round ^[1].
  • Nesting: This is the most challenging aspect. In nature they build carton nests on leaf undersurfaces. In captivity, you can try small acrylic nests or test tubes with cotton, but they may prefer something more naturalistic that mimics their arboreal lifestyle. Provide small chambers scaled to their tiny size.
• Behavior: These ants are very small and likely shy. They are arboreal foragers, probably foraging on leaves and branches for small insects, honeydew, and nectar. Their tiny size means escape prevention must be excellent, they can squeeze through gaps that seem impossible. They are not aggressive and pose no threat to keepers. Activity level is moderate, they forage in the canopy layer rather than on the forest floor.
• Common Issues: tiny size makes escape likely without fine mesh barriers, specialized arboreal nesting requirements are difficult to replicate in captivity, small colony size means slow growth and limited population, high humidity needs can lead to mold if ventilation is poor, very rare in the hobby, finding colony may be difficult

Housing and Nest Setup

Keeping Wasmannia iheringi presents a unique challenge because of their specialized arboreal nesting behavior. In the wild, they build small carton nests on the undersurface of leaves, a 2cm felt-like roof covering the leaf between veins ^[1]. This is nothing like typical ant nesting.

For captivity, your best options are small test tubes with cotton or small acrylic nests with tight chambers. The key is scale, these ants are tiny, so chambers should be small and passages narrow. A test tube setup with a water reservoir works well for founding colonies. For established colonies, you might experiment with naturalistic setups using artificial leaves or small structures they can build on.

Escape prevention is critical. Workers are only 0.5mm, meaning they can squeeze through gaps you didn't know existed. Use fine mesh on any ventilation holes, seal all joints with fluon or petroleum jelly, and check boundaries regularly. A single gap in your barrier is all it takes for these tiny ants to vanish.

Feeding and Diet

Wasmannia iheringi belongs to the tribe Attini, which includes fungus-growers, but the genus Wasmannia is not a true fungus-grower, they are generalist omnivores like most Myrmicinae. In the rainforest canopy, they likely forage for small insects, honeydew from aphids and scale insects, and nectar.

Feed them small protein sources like fruit flies, pinhead crickets, or small mealworms. Since they are so tiny, their prey items must be appropriately sized, springtails are an excellent choice. Offer sugar water, honey, or diluted honeydew as an energy source. Feed small amounts every 2-3 days and remove uneaten food to prevent mold.

Because they are arboreal foragers, they may prefer feeding in elevated positions rather than on the nest floor. Place food on small platforms or elevated surfaces in the outworld. ^[1]

Temperature and Humidity

These are tropical rainforest ants from the canopy layer. They require warm, humid conditions year-round, no hibernation or winter rest ^[1]. Keep temperatures in the range of 24-28°C. A heating cable on one side of the nest creates a temperature gradient that allows the ants to choose their preferred spot.

Humidity should be high, aim for 70-80% relative humidity. The forest canopy where they live is constantly humid. Use a water tube in the nest for drinking access, and keep the substrate consistently moist. However, balance humidity with adequate ventilation to prevent mold growth, which can quickly kill small colonies.

Avoid temperature fluctuations and cold drafts. These ants have never experienced cold conditions in their evolutionary history, and even brief exposure to cool temperatures can stress or kill them.

Colony Structure and Growth

Wasmannia iheringi colonies can be polygynous, meaning multiple queens can coexist in the same nest. One observed nest contained 27 workers, one dealate queen, four adult males, and brood of various sizes ^[1]. Another observation found a dense aggregation with two dealate queens, confirming polygynous colony structure is possible ^[1].

Colony size remains small compared to many common ant species. Based on observed natural colonies, full-grown colonies likely reach under 100 workers. This means your colony will never become massive, but what they lack in numbers they make up for in interesting behavior.

Growth is likely slow. With small colony sizes and tropical origins, expect gradual development. Queens produce eggs periodically, and development from egg to worker likely takes 6-10 weeks based on related species. Be patient, these ants are a long-term project, not a fast-growing species.

Behavior and Temperament

As arboreal ants, Wasmannia iheringi forages in the canopy layer rather than on the ground. They are likely shy and non-aggressive, focusing on collecting honeydew and small insects rather than defending territory. They pose no stinging threat to keepers, at 0.5mm, their stingers cannot penetrate human skin.

Their most interesting behavior is the carton nest construction. In captivity, you may observe them building similar structures if provided with appropriate materials. They create a felt-like material from plant fibers and secretions, shaping it into protective roofs over their nesting sites.

Activity levels are moderate. They are not hyperactive like some species, but they maintain consistent foraging activity. Watch for workers exploring the outworld, collecting food, and tending to brood. Their small size makes them fascinating to observe under magnification. ^[1]

Frequently Asked Questions

References