Crematogaster hullettii

Crematogaster hullettii

Crematogaster hullettii is a tiny myrmecophyte ant species native to Southeast Asia, specifically found in Borneo, Peninsula Malaysia, and Sumatra. Workers measure just 2.4-3.0mm and are medium to dark brown with a slightly darker head and gaster. Queens are relatively small at 6.2-7.0mm and uniformly dark brown. This species belongs to the Crematogaster borneensis group and is obligately associated with Macaranga plants, they nest exclusively inside the hollow stems of seedling Macaranga trees, particularly Macaranga hullettii, M. bancana, M. angulata, and M. umbrosa. In Peninsula Malaysia, they inhabit higher elevation sites above 500m like Genting Highlands and Fraser's Hill, while Borneo populations are mainly in lowland areas.

Quick Summary

• Difficulty: Hard
• Origin & Habitat: Southeast Asia (Borneo, Peninsula Malaysia, Sumatra), obligate plant-ants living inside Macaranga plant stems in tropical rainforest habitats at elevations from lowland to 500m+ ^[1]
• Colony Type: Colony structure is unconfirmed, this is an obligate plant-ant that lives inside Macaranga stems. Likely monogyne (single queen) based on typical Crematogaster patterns, but specific colony structure has not been documented.
• Size & Growth:
  • Queen: 6.2-7.0mm ^[1]
  • Worker: 2.4-3.0mm ^[1]
  • Colony: Unknown, likely small colonies typical of plant-ant species in hollow stems
  • Growth: Unknown, likely moderate based on typical Crematogaster development
  • Development: 6-8 weeks (estimated based on typical Crematogaster patterns) (Development timeline is not directly studied for this species. Estimates based on genus-level data for small Myrmicinae at warm temperatures.)
• Antkeeping:
  • Temperature: Keep warm at 24-28°C, these are tropical ants from Southeast Asia. A gentle heat gradient allows workers to regulate their temperature.
  • Humidity: High humidity (70-85%), they naturally live inside plant stems in humid tropical rainforest conditions. Keep the nest substrate consistently moist but not waterlogged.
  • Diapause: No, these are tropical ants that do not experience cold winters. They remain active year-round.
  • Nesting: This species is an obligate plant-ant that requires hollow stems or tubes to mimic their natural Macaranga host. Y-tong (AAC) nests with narrow chambers or test tube setups with plant stem mimics work well. They need tight, enclosed spaces scaled to their tiny 2-3mm worker size.
• Behavior: These are small, active ants with typical Crematogaster behavior, they are generally non-aggressive but will defend their nest vigorously. Workers are fast-moving and can be skittish. They have a gaster-raising display behavior when threatened. Escape prevention is critical due to their very small size, they can squeeze through tiny gaps. They are primarily arboreal (tree-dwelling) in nature.
• Common Issues: escape prevention is critical, their tiny 2-3mm size means they can slip through standard barrier setups, use fine mesh and tight-fitting lids, obligate plant-ant requirements make them difficult to house, they need hollow stem-like structures, not typical soil nests, high humidity requirements can lead to mold if ventilation is poor, wild-caught colonies may be difficult to establish as they are specialized to live inside specific plant structures, their symbiotic relationship with Macaranga means they may struggle in captivity without appropriate nesting structures

Natural History and Host Plant Association

Crematogaster hullettii is an obligate plant-ant, meaning it lives exclusively inside specialized structures called domatia that form in the hollow stems of Macaranga trees. This is a mutualistic relationship, the ants get shelter, and the trees get protection from herbivores and competing plants. The species specifically colonizes seedlings of non-waxy Macaranga species from the section Pachystemon, including Macaranga hullettii (which is named after this ant's discoverer), M. bancana, M. angulata, M. petanostyla, and M. umbrosa. In Peninsula Malaysia, this ant is restricted to higher elevation sites above approximately 500m elevation, while in Borneo it is mainly found in lowland areas. This elevation preference suggests they prefer cooler, more humid conditions than some related species. ^[1]

Housing and Nesting Requirements

This is the most challenging aspect of keeping C. hullettii. As obligate plant-ants, they need nesting structures that mimic the hollow stems of Macaranga plants. Standard soil nests or acrylic formicaria are not appropriate. The best captive setups include Y-tong (AAC) nests with very narrow chambers scaled to their tiny 2-3mm worker size, or custom setups using narrow glass or plastic tubes that simulate plant stems. You can also create a naturalistic setup using thin plant stems or bamboo sections. The nest chambers should be tight and enclosed, not the open spaces typical of larger ant species. Because they are arboreal by nature, they prefer vertical or angled nest orientations over horizontal ones.

Temperature and Humidity

As tropical ants from Southeast Asia, C. hullettii requires warm, humid conditions. Keep the nest area at 24-28°C, which is typical for tropical species. You can use a heating cable on one side of the nest to create a gentle temperature gradient, but avoid overheating. Place the heating on top of the nest rather than underneath to prevent excessive drying. Humidity should be maintained at 70-85%, which mimics the humid conditions inside plant stems in tropical rainforests. Use a water reservoir or moisture gradient in the nest so workers can choose their preferred humidity level. Mist the outworld occasionally but avoid letting the nest substrate become waterlogged, as this promotes mold.

Feeding and Diet

Like other Crematogaster species, C. hullettii is likely omnivorous with a preference for sugar sources and protein. In nature, they tend Macaranga trees for honeydew and also hunt small insects. In captivity, offer sugar water or honey water as a constant energy source. For protein, provide small live prey such as fruit flies, pinhead crickets, or small mealworms. Because of their tiny size, prey items should be appropriately sized, no larger than their gaster. Feed protein 2-3 times per week, removing any uneaten prey within 24 hours. They may also accept specialized liquid feeders designed for small ants.

Behavior and Colony Dynamics

Crematogaster ants have a distinctive defensive behavior, when threatened, they raise their gaster upward in a display position, ready to spray formic acid or adhesive secretions. This is their primary defense since they lack a powerful sting. Workers are active and fast-moving, typically foraging along plant stems and surfaces. Colonies are likely smaller than many common ant species, probably reaching only dozens to perhaps a hundred workers in captivity. The queen is relatively small at 6-7mm and is adapted for life inside narrow plant stems. These ants are not aggressive toward humans but will defend their nest vigorously against intruders.

Frequently Asked Questions

References