Lasius carniolicus

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Palearctic region – from Western Europe (France, Spain) through Central Europe (Germany, Poland, Austria) to Siberia, with populations in Afghanistan, Kyrgyzstan, and Pakistan. Inhabits xerothermous grassland, short-grassy mountain pastures, and dry pine forests at elevations up to 1650 m in Europe and 2600 m in Pakistan ^[1][2].
• Colony Type: Temporary social parasite – the queen invades a host colony of Lasius flavus or Lasius alienus, kills the host queen, and uses the host workers ^[3]. Colonies can be polygyne, with up to 265 queens recorded in a single nest ^[2]. Reproductives (winged queens and males) overwinter in the nest and the main nuptial flight season is September–October, though some populations may fly in spring ^[3][2].
• Size & Growth:
  • Queen: ~3.5-4 mm, barely larger than workers ^[2] – among the smallest queens in Lasius
  • Worker: 3.5-3.7 mm ^[1]
  • Colony: Up to approximately 360 workers in mixed colonies ^[2]
  • Growth: Moderate
  • Development: Estimated 6-8 weeks, based on typical Lasius development patterns (Because the queen uses host workers from the start, colony establishment is quicker than in claustral species.)
• Antkeeping:
  • Temperature: Keep around 20-24°C. This species prefers warm, dry conditions matching its xerothermous habitat. Provide a gentle gradient.
  • Humidity: Keep the nest relatively dry with one small moist area. Since L. carniolicus naturally lives in dry grasslands and pine forests, avoid high humidity. A Y-tong or plaster nest can help manage a gradient.
  • Diapause: Yes – required. As a temperate European species, the colony needs a winter rest period of 3-4 months at 5-10°C (roughly November to February).
  • Nesting: Y-tong or plaster nests work well. Provide a dry to moderately humid environment with a temperature gradient. Because the ant is a temporary parasite that naturally lives inside a host colony, a naturalistic setup with a connection to a host colony is ideal but complex to maintain.
• Behavior: Shy and secretive – L. carniolicus is largely subterranean and rarely comes to the surface except during nuptial flights. Workers are not aggressive and will retreat when disturbed. They produce a distinctive lemon scent when threatened, which serves as an alarm pheromone ^[5][6]. Escape risk is low: workers are moderate-sized and not particularly agile, but standard containment practices should still be followed. The species is cryptic and easily overlooked due to its underground lifestyle and small colony size.
• Common Issues: obtaining a colony is extremely difficult – this is a temporary social parasite, so you cannot simply collect a queen and start a colony, you need an established host colony (L. flavus or L. alienus) ^[2][3]., host species dependency makes this ant impractical for most hobbyists – without a host, the queen cannot establish a colony., colonies remain relatively small even when established – documented sizes are 105-358 workers with many queens ^[2]., the host colony may reject the parasite queen, leading to failure – the introduction process is delicate and rarely successful., cryptic lifestyle makes observation difficult – they rarely emerge onto surfaces.

Understanding the Parasitic Lifestyle

Lasius carniolicus is one of the few truly parasitic ants in the Lasius genus. Unlike typical ants where a queen founds a new colony alone, L. carniolicus queens must invade established colonies of other Lasius species – primarily Lasius flavus (the yellow meadow ant) or Lasius alienus ^[3][4]. The queen enters the host nest, kills the resident queen using chemical warfare, and then uses the existing host workers to raise her own brood. This is called 'temporary social parasitism' because the parasite queen eventually establishes her own reproductive colony while using the host workers initially ^[2][3].

This lifestyle explains why L. carniolicus queens are so small – they don't need the large fat reserves that claustral queens have, since they get food from the host colony from day one. The queens are physogastric (abdomen expands enormously with eggs), which allows them to produce large numbers of eggs ^[2].

For antkeepers, this means L. carniolicus cannot be kept in the traditional way. You cannot simply catch a queen and expect her to found a colony. Instead, you would need either an established mixed colony or the ability to introduce a L. carniolicus queen into an existing L. flavus or L. alienus colony – which is extremely challenging and rarely successful.

Housing and Nest Setup

Since L. carniolicus is a subterranean species that naturally lives in underground chambers within host ant nests, they do best in setups that allow humidity control while maintaining dry areas. A Y-tong or plaster nest with a water reservoir works well – these let you create a humidity gradient where the ants can choose their preferred zone. Keep the nest relatively dry with one small moist section, reflecting their natural xerothermous habitat.

Temperature should be maintained around 20-24°C with a gentle gradient if possible. This species naturally inhabits warm, sunny grasslands and pine forests, so they appreciate warmth. However, avoid extreme heat – temperatures above 30°C are not recommended.

Because this is a parasitic species requiring a host, the practical housing setup is complex. Most antkeepers would need to maintain both the host species (L. flavus or L. alienus) and introduce the parasite queen, which requires advanced husbandry skills. The outworld should be simple and escape-proof, with a standard Lasius-style setup. ^[1][2]

Feeding and Nutrition

In the wild, L. carniolicus workers feed primarily on honeydew from root aphids and other subterranean insects kept as 'cohabitants' in their underground nests ^[7]. They are not active foragers like some other Lasius species – instead, they tend underground aphid farms and consume the sugary secretions ^[7][3].

In captivity, offer sugar water or honey water as a constant food source, supplemented with small protein sources like fruit flies, small crickets, or mealworms. However, since they live in a host colony, they may be outcompeted for food by the host workers. The host species (L. flavus) also primarily feeds on honeydew, so both species have similar dietary requirements.

Feed sugar water or honey water constantly (refreshed every 2-3 days), and offer protein prey 1-2 times per week. Remove uneaten prey after 24 hours to prevent mold. Given their small size and secretive nature, they may not consume much – don't be alarmed if feeding seems minimal.

Seasonal Care and Diapause

As a European species, L. carniolicus requires a winter diapause. The main nuptial flight period is September–October ^[1][3], but in some areas reproductives have been collected in May ^[2], suggesting variation across the range. After mating, queens likely seek out host colonies.

To support the colony's natural cycle, provide a 3-4 month hibernation period at 5-10°C (roughly November to February). During the active season (April to October), maintain room temperature (20-24°C) with normal feeding. In late autumn, gradually reduce temperature to induce hibernation. Place the colony in a cool location (unheated garage, basement, or refrigerator) for winter. This rest period is essential for long-term health and reproductive development.

Note: If you have a mixed colony with host species, both will need diapause together.

Behavior and Defense

Lasius carniolicus is a shy, secretive species that spends most of its time underground. Workers are not aggressive and will typically retreat when threatened. However, they have a unique defense mechanism: when disturbed, they release a strong lemon-scented alarm pheromone from their mandibular glands. This scent contains citronellal compounds that alert nestmates and may deter predators ^[5][6][8].

The lemon scent is quite noticeable when the ants are handled or when a nest is disturbed – it's used in the field for identifying this species in Sweden ^[5]. They do not sting or bite, their primary defense is retreat and chemical deterrence.

Activity levels are low compared to many Lasius species. They are not prolific foragers and will not be visible outside the nest frequently. This makes observing the colony somewhat challenging compared to more active ants.

Finding and Obtaining Colonies

Finding L. carniolicus in the wild is difficult because of small colony sizes, subterranean lifestyle, cryptic nesting behavior, and scattered distribution. They nest under stones in sandy or limestone-based soils in warm, dry habitats. The nests often have a small flat mound of excavated soil but are otherwise inconspicuous ^[1].

In Europe, they are considered rare everywhere. In Germany, they are the rarest Lasius species ^[2]. They are often overlooked because they don't form the large visible mounds that L. flavus does, and they rarely come to the surface.

For antkeepers, obtaining a colony is the primary challenge. Options are extremely limited: (1) finding a mixed colony in the wild (requires expert identification), (2) purchasing from specialized dealers who have successfully established parasitic colonies (rare), or (3) attempting to introduce a queen into a host colony (advanced technique with low success rate). For most antkeepers, this species is not practical to keep – consider L. flavus or L. alienus as more accessible alternatives with similar care requirements.

Frequently Asked Questions

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