Polyergus bicolor

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Upper Mississippi Valley region, western Great Lakes to the Dakotas and southern Manitoba. Nests in rotting logs and fallen limbs in moist forest habitats ^[2][3].
• Colony Type: Dulotic (slave-making), requires a host Formica colony to survive. The Polyergus queen invades and kills the host queen, then uses host workers to raise her brood ^[2].
• Size & Growth:
  • Queen: Size data unavailable, no total length measurements for queens in research context.
  • Worker: 4.8-6.6 mm total length ^[1].
  • Colony: Size data unavailable.
  • Growth: Unknown, depends on host colony health.
  • Development: Unknown, development occurs within host colony. (No specific timeline data available.)
• Antkeeping:
  • Temperature: Keep at room temperature, roughly 20-24°C, as they are from temperate regions ^[3].
  • Humidity: Keep nest substrate consistently moist but not waterlogged, based on their moist forest habitat ^[2][3].
  • Diapause: Yes, likely requires winter diapause of 2-3 months at 5-10°C, inferred from northern distribution ^[3].
  • Nesting: Use naturalistic setups with rotting wood or standard test tubes for the host colony. Avoid acrylic nests, recommend Y-tong, plaster, or soil nests ^[2][3].
• Behavior: Polyergus bicolor workers are aggressive slave-makers but not particularly defensive toward keepers. Escape risk is moderate due to medium size, use standard barriers. Survival depends entirely on host colony ^[2].
• Common Issues: host colony collapse is fatal, without live host workers, Polyergus bicolor cannot survive ^[2]., maintaining two colonies doubles complexity and cost., queen introduction can fail if host colony rejects her., without regular raids, host worker numbers may decline.

Understanding Dulotic Ants

Polyergus bicolor is a dulotic ant, meaning it is a slave-maker. This is one of the most complex ant lifestyles to keep in captivity. Unlike typical ants where the queen raises her own workers, dulotic queens must invade an established colony of their host species, kill or replace the host queen, and trick the host workers into raising Polyergus brood instead of their own ^[2]. The host workers continue all normal colony functions, foraging, nursing brood, maintaining the nest, while the Polyergus workers primarily focus on raiding other colonies to steal more host pupae ^[1]. This means you cannot keep Polyergus bicolor alone. You must maintain a healthy colony of Formica subaenescens (or occasionally Formica neorufibarbis) as the host ^[1]. Without the host workers, the Polyergus portion of the colony will die.

Housing Requirements

You need two separate setups: one for the host Formica colony and one where the Polyergus queen and her workers will integrate. The host colony can be kept in standard test tubes, naturalistic setups with rotting wood, or nests made of Y-tong, plaster, or soil ^[2][3]. Formica ants prefer moist conditions, so keep the substrate damp. The Polyergus portion will essentially live within the host nest once the invasion is successful. For the initial introduction, place the Polyergus queen near the host colony entrance, she will release pheromones that trick the host workers into accepting her. This process can take hours to days and may fail. Monitor closely and be prepared to separate if the host workers attack aggressively.

Feeding the Colony

The host Formica workers will forage for food and feed the entire colony, including the Polyergus. You should feed the host colony a varied diet: sugar water or honey for energy, and protein sources like mealworms, crickets, or other insects. Formica ants are generalist feeders and typically accept most ant foods. The Polyergus workers will also accept some food directly but rely heavily on the host workers for nutrition. Keep a constant sugar source available and offer protein 2-3 times per week. ^[3]

Seasonal Care and Overwintering

Like other ants from their northern range, Polyergus bicolor likely requires a winter diapause period. During autumn, reduce temperatures gradually to around 5-10°C and keep them there for 2-3 months. This mimics their natural seasonal cycle and is important for colony health. Both the Polyergus and host portions of the colony will slow down during this period. Do not feed heavily during diapause and keep substrate slightly damp but not moist. Return to room temperatures gradually in spring when the colony becomes active again. ^[3]

The Raid: How They Acquire Slaves

One of the key behaviors of Polyergus bicolor is their raiding behavior. When a colony needs more host workers, Polyergus scouts locate nearby Formica nests and recruit raid parties. During a raid, Polyergus workers rush into the host nest and grab as many pupae as they can carry, then retreat quickly. The stolen pupae are raised by the host workers already in the colony, these emerging workers then become part of the workforce that supports the Polyergus ^[2][1]. In captivity, you may observe this behavior if you provide access to a secondary Formica colony, though this is not recommended as it can destabilize your primary host colony.

Frequently Asked Questions

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References