Lasius sakagamii

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Japan, found across Hokkaido, Honshu, Kyushu, and Yaku Island from sea level to 500 m altitude. Also recorded on the Korean Peninsula ^[4][3]. Prefers sun-exposed areas with sandy and alluvial soils: river banks, dry river beds, sand dunes, and road sides with sparse vegetation ^[4][5][1].
• Colony Type: Polygynous (multiple queens) and polydomous (multiple connected nest sites). Colonies can reach several hundred thousand workers. Queens are adopted by established colonies, and new colonies can form through budding ^[3][5][6]. May form supercolonies dominating large areas.
• Size & Growth:
  • Queen: 7-8 mm ^[1][2]
  • Worker: 2.5-3.5 mm ^[3][2]
  • Colony: Several hundred thousand workers ^[3][5]
  • Growth: Moderate
  • Development: 6-10 weeks (estimated based on related Lasius species) (Development time inferred from genus-level data for Lasius. Founding behavior is unconfirmed, queens may be adopted by existing colonies rather than starting independently ^[6].)
• Antkeeping:
  • Temperature: Keep at 20-24°C. Nuptial flights occur at temperatures above 22°C, suggesting they prefer warm conditions ^[4]. Room temperature is typically suitable, with a slight warm side in the enclosure if desired.
  • Humidity: Low to moderate. This species naturally inhabits dry, sandy areas like river banks and sand dunes, keep the nest relatively dry with good drainage. Provide a moisture gradient so ants can choose their preferred humidity ^[4][5].
  • Diapause: Yes. Based on temperate Japanese distribution (33°N to 45°N), colonies require a winter rest period. Reduce temperature to 10-15°C for 2-3 months during winter ^[7].
  • Nesting: Soil-nesting species. In captivity, use a test tube for founding, then transition to a formicarium with sandy substrate or a Y-tong nest. They need deep substrate (they build chambers down to 60 cm in the wild) and multiple chambers ^[4][5]. Avoid overly humid conditions.
• Behavior: Generally peaceful and non-aggressive, when threatened, workers typically flee rather than attack ^[1][2]. They are active foragers from early April to late October. Workers forage in sunny areas and will tend aphids for honeydew. They form weak covers on foraging paths. Escape risk is moderate, use standard Lasius barrier precautions. Colonies become very large, so plan for expansion.
• Common Issues: large colony size requires significant space, these ants can reach several hundred thousand workers and need room to expand ^[3]., polygynous colonies may have queen competition or adoption issues when introducing new queens., overwatering can cause fungal problems because they need dry habitat conditions., winter diapause is essential, keeping them active year-round can stress colonies., supercolonies may dominate any shared enclosure with other ant species.

Housing and Nest Setup

Lasius sakagamii needs a dry, sandy nesting environment that mimics their natural river bank and sand dune habitat. For founding, a standard test tube setup works well, though founding behavior is not confirmed, single queens can start colonies. Once the colony reaches 20-30 workers, transition to a formicarium with a sandy substrate mix or a Y-tong style nest with dry conditions.

These ants build deep nests in the wild, with chambers reaching 60 cm underground ^[4]. In captivity, provide as much vertical depth as possible with multiple connected chambers. Because they are polydomous (maintaining multiple nest sites), they appreciate having both a nest area and an outworld for foraging. Use an escape prevention barrier suitable for Lasius, these workers are small but not tiny, so standard fluon barriers work.

Avoid overly humid conditions. This species prefers bare sandy spots with sparse vegetation, so keep the nest relatively dry with good ventilation. A moisture gradient (damp on one end, dry on the other) lets the colony choose its preferred conditions.

Feeding and Diet

Like other Lasius species, Lasius sakagamii is omnivorous with a preference for sugar sources and honeydew from aphids. In captivity, provide a constant sugar source like sugar water, honey water, or diluted honey. They will also accept protein in the form of small insects (fruit flies, small crickets, mealworms).

In the wild, they attend root aphids (Sappaphis piri) and have been observed feeding on secretions from Paulownia trees ^[8][9]. They are less arboreal than some related species, preferring to forage on the ground in sunny areas rather than climbing extensively ^[1]. Feed protein 2-3 times per week for growing colonies, and keep sugar water available at all times.

Their foraging activity runs from early April to late October in the wild ^[1], so adjust feeding frequency seasonally, reduce significantly during winter dormancy.

Temperature and Seasonal Care

Lasius sakagamii originates from temperate Japan (33°N to 45°N latitude), so they experience distinct seasons. Keep the colony at 20-24°C during the active season (spring through fall). Nuptial flights occur when temperatures exceed 22°C on warm evenings with high humidity ^[4], indicating they prefer warm conditions.

Winter diapause is essential. From late October through early April, reduce temperatures to 10-15°C and reduce feeding. Place the colony in a cool, dark location like an unheated garage or basement. Do not feed during diapause. This rest period is crucial for colony health, keeping them active year-round can lead to stress and colony decline.

In summer, room temperature is typically suitable. If your room runs cool, a heating cable on one side of the nest can create a gradient, but ensure there's a cool side as well.

Colony Structure and Behavior

This is one of the more complex Lasius species to keep due to its polygynous (multi-queen) and polydomous (multi-nest) structure. Colonies can contain dozens of queens working together, and they maintain multiple connected nest sites that can span large areas ^[3][5].

Queens are adopted by established colonies, this is called "secondary polygyny", rather than founding colonies independently ^[6]. This means you may be able to introduce additional queens to an established colony, though success varies.

The species can form supercolonies that dominate entire habitats in the wild. In captivity, this means colonies can become extremely large (hundreds of thousands of workers) and may be aggressive toward other ant colonies if given the chance to expand.

Behaviorally, they are timid, when threatened, workers flee rather than engage in combat ^[1][2]. They are active foragers that search for food in sunny areas and maintain weak pheromone trails.

Unique Biological Traits

Lasius sakagamii has several unusual traits that make it interesting for antkeepers. First, about 20% of nests contain diploid males, males that developed from fertilized eggs rather than unfertilized ones ^[3][5]. This is genetically unusual since most ants use a system where males come from unfertilized eggs.

Second, they practice intranidal mating, queens mate with males inside the nest rather than during a nuptial flight, then disperse to found new colonies ^[4][6]. In nests without males, virgin queens will take nuptial flights to mate externally.

The species is closely related to Lasius niger but is distinctly polygynous whereas L. niger is typically monogyne (single queen) ^[10]. This makes L. sakagamii an interesting species for studying the evolution of colony social structure.

Frequently Asked Questions

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References