Strumigenys calvus

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Endemic to the Republic of Korea. Found in broad‑leaved humid forests on mountains (600-700 m) and on islands at lower elevations (∼60 m). Nests under stones on the shaded, damp forest floor ^[1][2].
• Colony Type: Single‑queen colonies (monogyne). No ergatoid reproductives have been observed, only alate gynes are known ^[1].
• Size & Growth:
  • Queen: 3.10-3.29 mm ^[1]
  • Worker: 2.58-2.96 mm ^[1]
  • Colony: Up to about 90 workers as seen in wild colonies ^[1]
  • Growth: Slow, based on typical Strumigenys patterns
  • Development: Estimated 8-12 weeks at optimal temperature (inferred from related Strumigenys) (Development is slow, colonies grow gradually over several years.)
• Antkeeping:
  • Temperature: Keep the colony cool, between 18-22 °C. Avoid temperatures above 25 °C. These ants come from temperate mountain forests, so a stable cooler range is best. ^[1]
  • Humidity: Very high humidity is essential. The nest substrate should be consistently moist but not waterlogged, think damp forest soil. A humidity gradient with a wet area and a drier area is recommended. ^[1]
  • Diapause: Yes, as a Korean endemic, a winter dormancy is needed. Reduce temperature to 10-15 °C for 3-4 months (roughly November - February). ^[1]
  • Nesting: Natural nests are under stones in humid soil. In captivity, use a naturalistic setup: a container with moist, loose substrate (soil/sand mix) and flat stones on top. A Y‑tong or plaster nest with narrow, well‑humidified chambers also works. Avoid large open spaces.
• Behavior: Peaceful and not aggressive toward keepers. Workers forage individually, hunting springtails and other micro‑arthropods with their trap‑jaw mandibles. Rarely sting. Escape prevention is critical due to their tiny size, use fine mesh (≤0.5 mm) and tight seals. ^[1]
• Common Issues: escape prevention is critical, their 2.6-3 mm size lets them slip through tiny gaps, use fine mesh and tight seals, slow growth can frustrate beginners, colonies develop slowly and stay under 100 workers, high humidity needs may cause mold if ventilation is poor, balance moisture with airflow, sensitivity to heat, temperatures above 25 °C can stress or kill the colony, wild‑caught colonies may carry parasites, quarantining is recommended

Housing and Nest Setup

Strumigenys calvus needs a setup that maintains high humidity while keeping them contained. A naturalistic terrarium works best: fill a container with moist, loose substrate (a mix of soil and sand), and place flat stones or bark pieces on the surface to mimic their natural under‑stone nesting sites. Alternatively, a Y‑tong or plaster nest with narrow chambers and good moisture retention can serve if the chambers are sized for 2-3 mm ants. Whatever you choose, escape prevention is top priority, use fine mesh (0.5 mm or less) on all ventilation, and ensure lids seal tightly. Even tiny gaps will lead to escapes. ^[1]

Feeding and Diet

These ants are specialized predators that need live, small prey. Their staple food in captivity should be live springtails, they are the right size and nutrition. Culture your own or buy them. Other tiny live insects like flightless fruit flies, micro‑crickets, or small termites may also be accepted. Feed every 2-3 days, offering prey no larger than the ant’s head. Remove uneaten prey after 24 hours to avoid mold. Sugar water or honey is not taken by this predatory species. ^[1][3]

Temperature and Seasonal Care

Keep the colony at 18-22 °C year‑round during the active season. They come from cool Korean mountain forests, so avoid temperatures above 25 °C. During winter, you must provide a dormancy period: drop the temperature to 10-15 °C for 3-4 months (roughly November through February). This triggers healthy seasonal cycles and is essential for long‑term colony health. Do not keep them warm all year. ^[1]

Behavior and Observation

Watching Strumigenys calvus hunt is one of the main rewards. Workers move slowly through the substrate, searching for springtails. When they detect prey, they snap their trap‑jaw mandibles shut with incredible speed, this is their primary hunting and defense mechanism. They are not aggressive toward humans and rarely try to sting. Colonies stay small (under 100 workers even when mature), so you can observe individual ants easily. The rust‑orange body with a black spot on the abdomen is distinctive and helps confirm the species. ^[1]

Frequently Asked Questions

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References