Crematogaster sewellii

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Madagascar and Comoros islands, found in high-altitude grassland, savannah, and woodland (800-1500m) in central/south-central highlands, and lower elevations (160-600m) in western regions ^[1][2]. Nests in soil or under stones ^[1][3].
• Colony Type: Colony structure is not documented in scientific literature. Based on typical Crematogaster patterns, likely single-queen colonies, though this requires confirmation for this specific species.
• Size & Growth:
  • Queen: Approximately 5-6mm total length, inferred from Crematogaster genus ^[1][4].
  • Worker: Approximately 3-4mm total length, inferred from Crematogaster genus ^[1][4].
  • Colony: Colony size is not directly documented. Based on related Crematogaster species, colonies likely reach several hundred workers.
  • Growth: Growth rate is unconfirmed. Crematogaster species typically develop from egg to worker in 4-8 weeks at optimal temperatures.
  • Development: 4-8 weeks (estimated based on typical Crematogaster development patterns) (Development time is not directly studied for this species. Estimates based on genus-level data for similar tropical Crematogaster ants.)
• Antkeeping:
  • Temperature: Keep at 22-26°C. This species comes from Madagascar's highland regions where temperatures are moderate. Provide a gentle temperature gradient so ants can self-regulate.
  • Humidity: Moderate humidity around 50-70%. Since they nest in soil and under stones in the wild, keep the nest substrate moist but allow some drying areas. Mist occasionally and provide a water tube.
  • Diapause: Diapause requirements are unconfirmed for this species. Madagascar has mild seasons, so a winter cool-down period (15-18°C for 2-3 months) may be beneficial but is likely optional.
  • Nesting: Ground-nesting species that prefers soil nests or spaces under stones. In captivity, a naturalistic setup with soil substrate or a Y-tong/plaster nest works well. Provide damp substrate and avoid overly dry conditions.
• Behavior: Crematogaster ants are known for their acrobatic behavior, they can raise their gaster over their thorax when threatened, giving them their common name 'acrobat ants'. They are generally not aggressive but will use this defensive display. Workers are active foragers that likely scavenge and tend aphids for honeydew. Their small size means escape prevention is important, use fine mesh and tight-fitting barriers. They are primarily ground-nesting but may forage in vegetation.
• Common Issues: escape prevention is critical due to their small size, they can squeeze through tiny gaps, colonies may be slow to establish initially, patience is needed during founding, wild-caught colonies may carry parasites that can cause colony failure, overheating must be avoided, they come from moderate elevations, not hot tropical lowlands, dry conditions can cause colony decline, monitor substrate moisture regularly

Natural History and Distribution

Crematogaster sewellii is endemic to Madagascar and the Comoros islands, making it a truly unique species for antkeepers. It occupies a remarkably broad elevation range, from 800-1500m in the central and south-central highlands down to 160-600m in western regions like the Makay massif and Beanka Reserve ^[1]. This flexibility suggests the species can adapt to various conditions within Madagascar's climate. In the wild, C. sewellii often lives alongside Crematogaster mafybe and Crematogaster degeeri, part of the distinctive degeeri-species-assemblage unique to Madagascar ^[1]. The species is strictly ground-nesting, found either directly in soil or beneath stones, it does not nest in trees or rotting wood like some related Crematogaster species ^[1][3]. This ground-nesting habit is important for captive care, as it indicates a preference for substrate-based nests over arboreal setups.

Housing and Nest Setup

For captive care, recreate their natural ground-nesting environment. A naturalistic setup with a soil substrate works best, use a mix of sand and soil that holds moisture well without becoming waterlogged. Alternatively, a Y-tong (AAC) nest with a dirt chamber or a plaster nest with damp substrate provides good humidity control. The nest should have chambers scaled appropriately for their small size, tight spaces help them feel secure. Include some Dekovit or similar material they can use to create tunnels. Since they nest under stones in the wild, you could place flat stones on top of the substrate surface. Outworld space should allow for foraging, these are active ants that will explore and collect food. Always provide a water tube, as hydration is essential. Escape prevention is critical due to their tiny size, even small gaps in tubing or lids can allow escape. ^[1][3]

Feeding and Diet

Based on typical Crematogaster behavior and the species' presence in grassland ecosystems, C. sewellii likely has an omnivorous diet. They probably scavenge for protein sources (dead insects, protein jelly) and collect honeydew from aphids or scale insects. In captivity, offer a varied diet: sugar water or honey as an energy source, and protein sources like small insects (fruit flies, small mealworms, crickets), freeze-dried shrimp, or specialized ant protein foods. Feed protein 2-3 times per week and keep sugar sources available constantly. Since they're small ants, portion sizes should be tiny, a few drops of sugar water and prey items smaller than their head width. Remove uneaten prey after 24-48 hours to prevent mold.

Temperature and Seasonal Care

Maintain temperatures between 22-26°C, avoiding extremes on either end. This species comes from Madagascar's highland regions where temperatures are moderate year-round, not from hot tropical lowlands. A heating cable on one side of the nest can create a gradient, but monitor carefully, overheating is a common killer of Madagascar species. Room temperature in the low-to-mid 20s°C is often ideal. Regarding diapause: Madagascar has mild seasons without harsh winters, so a strict hibernation may not be required. However, a slight cool-down period in winter (15-18°C for 2-3 months) may benefit colony health and simulate natural cycles. Reduce feeding during this period and ensure some moisture remains available. Observe your colony's behavior, if they remain active, a cool-down is optional rather than mandatory. ^[1]

Behavior and Handling

Crematogaster sewellii displays the characteristic 'acrobat' behavior the genus is known for, when threatened, workers can raise their gaster over their thorax in a defensive posture, allowing them to spray formic acid from a distance. This makes them more interesting to watch than many passive ants, but also means they can be defensive. They are not typically aggressive toward humans and rarely sting, but the spray can be irritating. Their small size means they are excellent climbers and can scale smooth surfaces easily. When handling or observing, avoid sudden movements that might trigger defensive responses. In the outworld, they will actively forage and explore, making them engaging pets. Their large eyes suggest they may rely more on visual cues than some other ant species. ^[1]

Frequently Asked Questions

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References