Crematogaster evallans

Crematogaster evallans

Crematogaster evallans is a medium-sized Myrmicinae ant found throughout the Neotropical region, from Costa Rica through Colombia to Brazil. Workers measure about 2.5-3mm and are dark red-brown to nearly black in color, with distinctive long whitish hairs covering their body. They have a subquadrate head with eyes that project beyond the lateral margins, and their propodeal spines are thin and relatively long. This species is strongly arboreal, living in wet forest habitats where it forms large but infrequently encountered colonies. In the wild, they create visible trunk trails on trees, with workers rapidly descending and fanning out across the ground or low vegetation in search of resources. Queens show morphological features that may indicate social parasitic behavior, though this remains unconfirmed.

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Wet forest habitats throughout the Neotropical region, Brazil, Colombia, Costa Rica, and Guatemala. Found in both lowland rainforest and higher elevation forest fragments ^[1][2][3].
• Colony Type: Large colonies with unclear social structure. Observed colonies appear to be polydomous (spread across multiple nest sites), with workers and brood scattered across many dead branches in the canopy. Queens may exhibit social parasitic morphology, but colony founding behavior remains unconfirmed ^[1].
• Size & Growth:
  • Queen: Unconfirmed, queen measurements not directly documented, but related species suggest 5-7mm
  • Worker: Approximately 2.5-3mm based on HW 0.686-0.742mm ^[1]
  • Colony: Large colonies, estimated hundreds to over 1000 workers based on field observations of extensive trunk trails ^[1]
  • Growth: Moderate, likely slower than tropical specialists due to large colony size at maturity
  • Development: Unknown, no direct development data for this species. Based on typical Crematogaster patterns in tropical regions, estimate 6-10 weeks at optimal temperature (Development timeline is unconfirmed. Related tropical Crematogaster species typically take 6-10 weeks from egg to worker.)
• Antkeeping:
  • Temperature: Keep at 24-28°C. This species comes from wet tropical forests, so warmth and humidity are important. A gentle gradient allowing workers to self-regulate is recommended
  • Humidity: High humidity, aim for 70-85%. These ants live in wet forest environments and need consistently moist conditions. Provide a water reservoir in the nest and mist occasionally, but ensure good ventilation to prevent mold
  • Diapause: No, as a tropical species, they do not require hibernation. Maintain consistent warm conditions year-round
  • Nesting: Arboreal setup recommended. In captivity, they do well in Y-tong nests, plaster nests with multiple chambers, or naturalistic setups with dead branches/twigs. They prefer enclosed spaces and will nest in pre-existing cavities. Avoid fully artificial test tube setups, they need more complex, multi-chambered housing ^[1]
• Behavior: Active and aggressive foragers. Workers move quickly in columns and will readily defend their territory. They are arboreal by nature and spend significant time on vegetation. They have a functional stinger but are too small to cause meaningful pain to humans. Escape prevention is important, they are small and can squeeze through small gaps. Provide foraging areas with access to vegetation or branches ^[1].
• Common Issues: tropical humidity requirements mean mold can quickly become a problem without proper ventilation, arboreal nature means they need more vertical space and climbing structures than ground-nesting ants, large colony size at maturity requires spacious formicarium setup, small nests will lead to stress and abandonment, colony founding is poorly understood, wild colonies may have social parasitic elements that are difficult to replicate in captivity, they are fast-moving and can escape through tiny gaps, use fine mesh and tight-fitting barriers

Natural History and Distribution

Crematogaster evallans is found throughout the Neotropical region, with confirmed populations in Brazil, Colombia, Costa Rica, and Guatemala ^[3][2]. In Colombia, they have been recorded in Chocó, Huila, Magdalena, Meta, Santander, and Valle departments ^[2]. This species strongly prefers wet forest habitats and is classified as an arboreal vegetation inhabitant ^[4]. They are considered a low-density species, large colonies exist but they are infrequently encountered in the wild ^[1]. Field observations in Costa Rica's Corcovado and Manuel Antonio national parks show workers moving in rapid columns down tree trunks, then fanning out across the ground or low vegetation below. In one notable observation, worn trails in moss on a tree trunk suggested a large colony with regularly used trunk trails ^[1]. They have also been found in both ground litter and vegetation layers ^[5].

Nesting Behavior

This species is strongly arboreal, nesting in dead branches and twigs high in trees. The only nest ever observed in the wild was located about 4 meters up in a small tree, lodged in a vine tangle. The dead branches had been hollowed out by termites, and abandoned termite carton material filled the interiors. Workers and alate queens were thinly scattered throughout the branches, with no obvious colony center, suggesting the branches contained only part of a much larger colony living higher in the tree canopy ^[1]. This polydomous (multi-site) nesting pattern means these ants spread their colony across several nest locations rather than having a single central nest. In captivity, they do best in setups that mimic this, Y-tong nests, plaster nests with multiple connected chambers, or naturalistic terrariums with dead branches/twigs they can colonize. They prefer enclosed spaces and will readily move into pre-existing cavities.

Feeding and Diet

Crematogaster evallans is classified as omnivorous-detritivorous in trophic studies ^[6]. In the wild, they likely forage for honeydew from aphids and scale insects, collect dead insects, and scavenge organic matter. They have been observed foraging in columns on tree trunks and ground vegetation, suggesting active resource collection. In captivity, offer a varied diet including sugar water or honey as a constant energy source, small insects (fruit flies, small crickets, mealworms) as protein, and occasional fruits or seeds. Their arboreal foraging behavior suggests they may prefer feeding stations placed at various heights rather than just on the ground. Feed protein sources 2-3 times per week and keep sugar water available at all times.

Temperature and Humidity Requirements

As a wet forest species from tropical regions, Crematogaster evallans requires warm and humid conditions. Keep the nest area at 24-28°C with a gentle gradient allowing workers to self-regulate their temperature preference. Humidity should be maintained at 70-85%, this is higher than many common ant species. Provide a water reservoir in the nest and mist occasionally, but ensure adequate ventilation to prevent mold buildup. Since they come from environments with consistent year-round temperatures, do not allow temperatures to drop significantly. Avoid placing the nest near air conditioning vents or in cool rooms. A small heating cable on one side of the nest can help maintain warmth, but monitor carefully to avoid overheating and excessive drying.

Colony Structure and Social Organization

The social structure of Crematogaster evallans remains poorly documented. Field observations show large colonies with workers and brood scattered across multiple nest sites in the canopy, suggesting a polydomous (multi-site) colony structure ^[1]. The queen exhibits morphological features often associated with social parasitism, specifically, the propodeum slopes obliquely from the postscutellum in a pattern similar to the acuta-group queens known for parasitic behavior ^[1]. However, colony founding behavior has never been observed, so whether they are actually socially parasitic remains unknown. The presence of numerous inquiline beetles and silverfish in their nests suggests they may host commensal organisms, similar to other arboreal Crematogaster species ^[1]. For antkeepers, this means their exact colony structure (monogyne vs polygyne) is unclear, and introducing multiple unrelated queens is not recommended without more information.

Handling and Temperament

Crematogaster evallans workers are active and quick-moving, with an aggressive foraging style. They will readily defend their nest and resources. They possess a stinger but are too small (around 2.5-3mm) to penetrate human skin in most cases, the sting would be negligible even if they managed to pierce. Their small size means escape prevention is critical, they can squeeze through remarkably small gaps. Use fine mesh on any ventilation holes and ensure all connections are tight-fitting. When disturbed, workers may raise their abdomen (the characteristic 'cocktail' posture of Crematogaster) and release alarm pheromones to recruit nestmates. They are not suitable for frequent handling but can be observed fascinatingly through the walls of a well-designed formicarium. ^[1]

Frequently Asked Questions

References