Temnothorax americanus

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Eastern North America, from Quebec and Ontario south to Georgia and Florida, west to Kansas, Michigan, Illinois, Missouri, and Texas. Found in deciduous forests and semi-open woodlands, nesting in acorns, hickory nuts, sticks and dead roots in leaf litter, and in nests of other Temnothorax species ^[1][8][6].
• Colony Type: Obligate social parasite, requires host Temnothorax workers to survive. Small colonies typically contain 4-5 slavemaker workers and about 30 enslaved host workers, though larger colonies can reach 50 slavemakers and 300 slaves ^[5][1]. Colonies are polydomous (multiple connected nests) with only one nest containing the queen ^[9]. Strictly monogynous (single queen per colony) and monandrous (queen mates with one male) ^[9][10].
• Size & Growth:
  • Queen: 2.7-3.5 mm ^[2]
  • Worker: 2.5-2.75 mm ^[1]
  • Colony: Typically 4-5 slavemaker workers with ~30 slaves, maximum up to 50 slavemakers and 300 slaves ^[5][1]
  • Growth: Slow
  • Development: Unknown, likely 6-10 weeks based on related Temnothorax species (No specific development data available for this species. Related temperate Temnothorax species typically take 6-10 weeks from egg to worker at optimal temperatures. The estimate is based on related species.)
• Antkeeping:
  • Temperature: Keep at cool room temperatures, roughly 18-22°C, typical of forest floor habitat in temperate forests for habitat].
  • Humidity: Moderate humidity. Keep nest substrate slightly moist but not waterlogged, reflecting the leaf litter microhabitat].
  • Diapause: Yes, requires a winter rest period of 2-3 months at cooler temperatures (around 5-10°C), consistent with temperate origin].
  • Nesting: Tiny cavities, acorns, hickory nuts, sticks, or small artificial nests with narrow chambers scaled to their 2.5mm size. Must be kept with host colony ^[1][2]
• Behavior: Highly specialized social parasite that cannot survive without host workers. Slavemaker workers do not forage, feed themselves, or care for brood, enslaved host workers perform all these tasks via trophallaxis ^[11]. Workers form dominance hierarchies, dominant workers become fertile and account for over 70% of male offspring ^[9][12]. During summer, scouts search for host colonies and conduct raids using propaganda pheromones from their Dufour's gland to panic host defenders ^[5]. Colonies are small but aggressive during raids, approximately 19% of participating slavemaker workers are killed during attacks ^[13]. Escape risk is moderate due to small size but colonies remain confined to their nest area.
• Common Issues: requires live host colony, this species cannot survive without enslaved Temnothorax workers to feed and care for it, host rebellion, enslaved workers can kill up to two-thirds of parasite brood, especially in mature colonies, queen establishment failure, less than 7% of queens successfully establish new colonies in the wild, small colony size means any losses are significant and difficult to recover, dominance hierarchies within colonies can lead to conflict and reduced colony cohesion

The Slave-Making Lifestyle

Temnothorax americanus is an OBLIGATE social parasite, it cannot survive without host workers. This is perhaps the most critical point for any keeper: you must maintain both the slavemaker colony AND a healthy host colony simultaneously ^[11]. Unlike normal ants, slavemaker workers do not forage, feed themselves, or care for brood. They rely entirely on enslaved host workers to feed them through trophallaxis (mouth-to-mouth food sharing) and to care for their brood ^[11]. If separated from their slaves, slavemaker workers will starve to death even if food is available ^[11]. The species enslaves three common Temnothorax species: T. longispinosus, T. curvispinosus, and T. ambiguus ^[3][8]. Queens establish new colonies by invading host nests, killing or driving away the host queen and workers, then appropriating the existing brood. When that brood ecloses, the resulting host workers become the slavemaker's first slaves ^[1].

Host Colony Requirements

Because this is an obligate parasite, successful keeping requires establishing a host colony FIRST, then introducing the slavemaker. The best hosts are Temnothorax longispinosus, T. curvispinosus, or T. ambiguus, all common and relatively easy to keep ^[3]. Host colonies should be established in their own nest setup before introducing slavemakers. The slavemaker queen will need to invade and take over the host nest, so housing them in separate connected setups allows for this natural behavior. In the wild, approximately 1 in 15 host colonies of T. curvispinosus is enslaved by T. americanus ^[1]. Keep in mind that host workers are not passive victims, they can and do fight back. In fact, enslaved workers engage in "host rebellion" and may kill up to two-thirds of the parasite's female brood, particularly queen and worker pupae ^[14]. This is a natural defense mechanism that helps host colonies survive parasitic invasion.

Feeding and Nutrition

Feeding is straightforward in principle but complex in practice. Slavemaker workers cannot feed themselves, they must be fed by their enslaved hosts ^[11]. This means you offer food to the HOST workers, who then share it with the slavemakers via trophallaxis. Offer the host colony standard Temnothorax fare: small insects (fruit flies, pinhead crickets, mealworms), sugar water, and honey. The host workers will distribute food throughout the colony including to the slavemakers. Do not expect slavemakers to directly accept food offered to them. One interesting note: slavemaker workers have been observed consuming eggs laid by enslaved workers, this is the first recorded instance of independent feeding behavior in this species ^[9].

Raiding Behavior and Chemical Warfare

One of the most fascinating aspects of this species is its raiding behavior. During summer months, slavemaker workers leave their colony as scouts searching for nearby host colonies ^[13]. When a scout finds a suitable host nest (preferentially larger colonies with more workers), she can either attack directly or return to recruit a raiding party via tandem running ^[13]. During raids, slavemakers use propaganda pheromones from their Dufour's gland to induce panic in host workers, preventing organized defense ^[5]. They also mimic the cuticular hydrocarbon profiles of their host species to avoid detection, in areas with a single host species they closely match that host's CHC profile, while in areas with multiple hosts they produce an intermediate profile ^[5]. Despite this chemical warfare, approximately 19% of participating slavemaker workers are killed during raids, and about one-third of all raiding colonies lose at least one worker ^[13]. After a successful raid, slavemakers carry host eggs, larvae, and pupae back to their own nest. These stolen brood eclose as workers that become enslaved to the slavemaker colony ^[1].

Colony Organization and Social Structure

Temnothorax americanus colonies have a complex social structure. Colonies are polydomous, meaning they maintain multiple connected nests, but only one nest contains the queen ^[9]. Within the colony, workers form clear dominance hierarchies through antennal boxing and other behaviors, dominant workers become fertile and produce the majority of male offspring ^[9]. In fact, workers produce over 70% of all males in a colony, while the queen produces the remaining males and all females ^[9][12]. This is unusual, in most ant species, only the queen produces males. Higher-ranking workers lay more eggs, have longer ovarioles, and are fed more often by slaves ^[9]. Interestingly, dominant workers rarely participate in raiding, they stay in the nest and reproduce, while lower-ranking workers do the dangerous scouting and raiding work ^[13]. Relatedness among nestmates is high (r=0.66) due to monogyny and monandry ^[9].

Temperature and Seasonal Care

As a temperate species from eastern North America, T. americanus experiences distinct seasons in the wild. Keep colonies at cool room temperature (roughly 18-22°C), this matches their natural forest floor habitat]. During winter, colonies likely require a diapause period of 2-3 months at cooler temperatures around 5-10°C, similar to other temperate Temnothorax species. This winter rest is important for colony health and reproductive behavior. In captivity, you may observe reduced activity during winter months even without formal hibernation setup. The species shows distinct seasonal activity patterns, raiding primarily occurs during summer months, while winter is spent in relative dormancy ^[13]. Avoid keeping them too warm year-round as this may disrupt their natural cycles.

Legal and Ethical Considerations

This species is listed as Vulnerable (VU D2) on the IUCN Red List due to its specialized parasitic lifestyle and dependence on specific host species ^[6][7]. In the wild, less than 7% of queens successfully establish new colonies ^[13], making them naturally rare. Before keeping this species, check local regulations regarding collection and possession of native ant species. In some states, collecting native ants may require permits. Additionally, NEVER release this or any non-native species into the wild, while T. americanus is native to eastern North America, releasing captive colonies could spread disease to wild populations or disrupt local ecological balances. If you can no longer keep your colony, contact a local ant keeper or entomological society to rehome it responsibly.

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References