Lasius orientalis

Lasius orientalis

Lasius orientalis is a small jet-black ant belonging to the subgenus Dendrolasius, known for their distinctly flattened antennae and thick, low petiolar scale. Workers measure 3.0-3.5mm and have a characteristic inverted U-shaped petiole profile when viewed from the side. This species is notable for being a temporary social parasite, the queen invades colonies of Lasius flavus (the yellow meadow ant), kills the host queen, and uses the host workers to raise her first brood before her own workers eventually take over ^[1].

This species inhabits mountainous forest regions across the Russian Far East, Korean Peninsula, and northern Japan. It is considered rare in the wild, with nuptial flights occurring in July and August ^[1][2]. The jet black coloration and highly flattened scapes make this species distinctive within the genus Lasius.

Quick Summary

• Difficulty: Hard
• Origin & Habitat: Mountainous forest areas of Russian Far East (Amursky and Primorsky Regions, Islands Shikotan and Kunashir), Korean Peninsula, and Japan (Hokkaido, northern and central Honshu) ^[3][4]. Prefers forested habitats at higher elevations.
• Colony Type: Temporary social parasite, queen requires invasion of Lasius flavus host colony to establish. After the host queen is killed, the parasite queen uses host workers to raise her first brood until her own workers emerge.
  • Colony: Monogyne
  • Queen: Socially parasitic, Temporary parasitic
• Size & Growth:
  • Queen: Estimated 6-8mm based on related Dendrolasius species
  • Worker: 3.0-3.5mm ^[1]
  • Colony: Unknown for this species, likely similar to other Dendrolasius species reaching several thousand workers
  • Growth: Moderate, initial growth depends on host colony integration
  • Development: Unknown for this species. Based on typical Lasius patterns, expect 6-10 weeks at optimal temperature. (Development timeline is not directly studied. Initial colony growth depends on successful host integration rather than typical claustral founding.)
• Antkeeping:
  • Temperature: Keep at 18-22°C. As a temperate species from northern Japan and Russian Far East, they prefer cooler conditions than tropical ants. Room temperature within this range is typically suitable.
  • Humidity: Moderate humidity around 50-70%. Forest-dwelling species prefer substrate that holds some moisture but isn't waterlogged. Provide a water tube in the outworld.
  • Diapause: Yes, this temperate species requires winter hibernation. Reduce temperature to 5-10°C for 3-4 months during winter (roughly November-February in the Northern Hemisphere).
  • Nesting: Standard Lasius setups work well once colony is established. Test tubes for founding, then transition to formicarium with soil or plaster nest. The key challenge is the initial establishment requiring a host colony.
• Behavior: Generally peaceful and not aggressive. Workers are small at 3-4mm and not particularly defensive. As a temporary social parasite, the founding queen must be introduced to a host Lasius flavus colony, this is the critical challenge for keepers. Once established, colonies are manageable and not prone to escaping. Workers forage for honeydew and small insects.
• Common Issues: Establishment failure, getting the queen to integrate with a host L. flavus colony is difficult and many attempts fail, Colony collapse if host workers die before parasite queen's workers emerge, Rare species, wild colonies are difficult to locate and collect, Hibernation mortality if temperature isn't properly lowered, Slow growth once established compared to non-parasitic species

Understanding Temporary Social Parasitism

Lasius orientalis is a temporary social parasite, meaning its queen cannot found a colony alone like most ants. Instead, a newly mated queen must find and invade an established colony of Lasius flavus (the yellow meadow ant). The host colony must be queenless for the invasion to succeed, either a naturally queenless fragment or one where you've removed the queen. The invading queen kills or replaces the host queen and uses the host workers to raise her first brood. This is a delicate process that often fails, which is why this species is considered challenging to keep ^[1].

The key to success is timing and preparation. The host colony should be healthy with plenty of workers but no queen. Introduce the parasite queen carefully, some keepers use a introduction tube or chamber where the two can gradually acclimate. The host workers will initially attack the intruder, but if they accept her (which happens when they detect her cuticular hydrocarbons), they will begin caring for her eggs and larvae. Over time, the parasite queen's own workers will emerge and gradually replace the host workers.

Housing and Setup

For the initial establishment phase, you will need both a host Lasius flavus colony and housing for the parasite queen. A standard test tube setup works for the parasite queen, but she needs access to the host colony. Some keepers use a connected setup where the queen can move between chambers, while others introduce her directly to a queenless host colony fragment.

Once the colony is established (parasite queen has her own workers), standard Lasius housing works well. A Y-tong (AAC) nest or plaster formicarium with a connected outworld provides ideal conditions. The nest should have chambers scaled to their small worker size. Keep the nest area at stable room temperature (18-22°C) with moderate humidity. A water tube in the outworld ensures they have access to moisture. Lighting isn't critical, these are forest ants that prefer dimmer conditions.

Feeding and Nutrition

Once established, Lasius orientalis workers feed like other Lasius species, primarily on sugar sources (honey water, sugar water) and protein (small insects). In the wild, they tend aphids and feed on honeydew, so sugar water should be available at all times. For protein, small crickets, fruit flies, and mealworm pieces work well. Feed protein 2-3 times per week, removing uneaten prey after 24 hours.

During the parasitic founding phase, the host workers feed both the parasite queen and her brood. Once your colony has its own workers, they will readily take sugar water and protein from the outworld. The small worker size means prey items should be appropriately sized, very small pieces or small insects.

Seasonal Care and Hibernation

As a temperate species from northern Japan and the Russian Far East, Lasius orientalis requires a winter hibernation period. In captivity, this means reducing temperatures to roughly 5-10°C for 3-4 months. This typically coincides with late autumn through early spring (November through February in the Northern Hemisphere).

Before hibernation, ensure the colony is well-fed, workers should have full crops. Reduce temperature gradually over 1-2 weeks. During hibernation, check periodically that the setup doesn't dry out completely, but minimal maintenance is needed. In spring, gradually warm the colony back to room temperature and resume normal feeding. Colonies that don't receive proper hibernation may have reduced longevity or fail to produce reproductive castes the following season.

Behavior and Temperament

Lasius orientalis workers are small and relatively docile. They are not aggressive and don't have a painful sting. Their small size (3.0-3.5mm) means they can escape through small gaps, so escape prevention is important, use fluon on test tube rims and ensure any connections between nest and outworld are secure.

The most interesting behavior is the parasitic integration process itself. Once established, the colony behaves much like a normal Lasius colony, workers forage for sugar and protein, tend brood, and expand their nest. The transition from host-dependent to self-sufficient is fascinating to observe. Workers are moderately active and will explore the outworld regularly. ^[1]

Frequently Asked Questions

References