Temnothorax arimensis

Quick Summary

• Difficulty: Easy
• Origin & Habitat: Japan (Hokkaido, Honshu, and Nansei Islands) in the Palaearctic region. Nests in soil or dead twigs from lowlands to about 1,000m elevation ^[1][2].
• Colony Type: Unconfirmed, no literature confirms monogyne or polygyne. Based on typical Temnothorax patterns, likely single-queen colonies but not certain.
• Size & Growth:
  • Queen: Size data unavailable, inferred from Temnothorax genus, queens likely 4-6mm.
  • Worker: 2mm ^[1]
  • Colony: Unknown, inferred from Temnothorax genus, up to a few hundred workers.
  • Growth: Moderate
  • Development: Unknown, estimated 6-10 weeks based on generic Temnothorax development ^[2] (Development time depends heavily on temperature, warmer conditions speed it up, cooler slows it down)
• Antkeeping:
  • Temperature: Room temperature (18-24°C) is fine. Create a small warm spot (around 24°C) with a heating cable on one side so the colony can pick where it wants to be.
  • Humidity: Keep substrate lightly moist but not soggy. These ants nest in soil and dead twigs, so they need some moisture but also dry spots.
  • Diapause: Inferred from its temperate range: northern populations (Hokkaido) probably need a winter cool period (10-15°C for 2-3 months). Southern populations may need less. Watch for natural slowdown in activity.
  • Nesting: Y-tong (AAC) nests with narrow chambers work well. Small test tube setups also good. Provide tight spaces, the workers are only 2mm and feel secure in snug chambers. Use soil or dead twigs if you want a naturalistic nest.
• Behavior: Docile, non-aggressive (inferred from genus). They move slowly and don't sting, the defense mechanism is smearing venom, not stinging. Escape prevention is critical: their tiny 2mm size lets them slip through gaps that larger ants would ignore. Use fine mesh (0.5mm or smaller) and seal all lid joints. They'll probably use tandem running to recruit nestmates, but this is inferred from related species.
• Common Issues: escape prevention is critical due to tiny 2mm workers, they can squeeze through almost any gap, small colony size means slow growth, patience is needed for noticeable expansion, wild-caught colonies may have parasites or be stressed from collection, overfeeding can cause mold in small nests, remove uneaten prey within 24 hours, maintaining proper moisture without flooding a test tube requires careful water management

Housing and Nest Setup

Because workers are only 2mm, you need a nest with very small chambers. A Y-tong (AAC) nest with narrow, shallow chambers is ideal. A test tube with a cotton plug and water reservoir also works, as long as the tube isn't too big. Avoid large, open spaces, these tiny ants get stressed in wide areas. The outworld should be small, with a little dish for sugar water and another for small prey. Escape prevention is the top priority: use fine mesh (0.5mm or smaller) on vents, seal lid edges, and check any tube connections. Even a gap of 1mm will let them out ^[1].

Feeding and Diet

This ant is a generalist feeder (inferred from its genus). Offer small live prey like fruit flies, pinhead crickets, or tiny pieces of mealworm, sized to fit the 2mm workers. They also take sugar water or diluted honey. In the wild they probably catch small insects and tend aphids for honeydew, so a mix of protein and sugar works. Feed live prey 2-3 times a week, remove leftovers within a day to stop mold. Keep sugar water always available, replacing it every few days to prevent fermentation.

Temperature and Seasonal Care

Room temperature (18-24°C) is fine year-round. A small heat mat on one side of the nest (on top, not underneath to avoid drying the substrate) gives a warm zone around 24°C, letting the colony choose. For winter, northern populations (Hokkaido) likely need a cool period: put them at 10-15°C for 2-3 months. Southern populations may need only a short chill or none. Watch your colony, if they become sluggish in winter, that's a cue to cool them. Never freeze them, use a cool basement or refrigerator (not freezer) ^[1].

Behavior and Colony Dynamics

Temnothorax arimensis is calm and easy to observe. They likely use tandem running, a forager who finds food leads a nestmate back by touch, not by laying a pheromone trail. This is a common behavior in the genus but hasn't been confirmed for this species. Colonies stay small, probably a few hundred workers at most, which makes them manageable for years. The queen's founding behavior is unknown, keepers can try a standard test tube setup and hope she is claustral (sealed in and using stored fat) as is typical for many Temnothorax. Patience is needed during founding, the first workers may take weeks to appear. ^[1]

Frequently Asked Questions

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References