Temnothorax curvispinosus

Temnothorax curvispinosus - "Bent-spined Acorn Ant"

Temnothorax curvispinosus is a small yellow ant native to eastern North America, easily recognized by its very long, inwardly curved propodeal spines that sit close together at the base ^[1]. Workers measure about 2.4mm in length, while queens are larger at 3-3.3mm ^[2]. These ants are cavity-nesting specialists that live inside fallen acorns, hickory nuts, hollow twigs, and other small plant cavities on the forest floor ^[3]. They are one of the most thoroughly studied ant species in the eastern United States, making them excellent candidates for antkeepers who want to observe complex social behaviors ^[4]. This species is facultatively polygynous, meaning colonies can have either a single queen or multiple queens working together, and they are polydomous, meaning a single colony may occupy multiple nest sites ^[5][6].

Quick Summary

• Difficulty: Easy
• Origin & Habitat: Eastern United States, from Maine south to Florida and west to Texas, living in deciduous forest habitats ^[7]. They nest in preformed plant cavities like acorns, hickory nuts, hollow twigs, and dead branches in leaf litter ^[8].
• Colony Type: Facultatively polygynous, colonies can have one queen (monogyne) or multiple queens (polygynous). Queenless colonies are common, and workers can lay eggs to produce males. Colonies are also polydomous, meaning they spread across multiple nest sites in summer but coalesce into a single cavity for winter ^[5][9].
  • Colony: Optionally polygyne
  • Founding: Claustral, Pleometrosis
• Size & Growth:
  • Queen: 3-3.3mm ^[2]
  • Worker: 2.4mm ^[2]
  • Colony: Typically 80-100 workers, occasionally up to 369 workers in larger colonies ^[7][10]
  • Growth: Moderate
  • Development: 6-8 weeks (estimated based on typical Temnothorax development) (Egg laying begins mid-April and continues until early September. All eggs develop into larvae by October, with larvae overwintering and pupating in early June ^[10].)
• Antkeeping:
  • Temperature: Keep at room temperature, around 20-24°C. They can tolerate temperatures from 11.6°C to 34.1°C for colony growth, with optimal growth at intermediate warming of 2-4°C above ambient ^[11]. Avoid temperatures above 34°C as this stops colony growth. Limited activity below 20°C ^[12].
  • Humidity: Keep nest substrate slightly moist but not waterlogged. In the wild, colonies move within their acorn to avoid overly damp or moldy areas ^[13]. They prefer stable conditions rather than extreme moisture.
  • Diapause: Yes, colonies are less active in winter and may cluster together in a single cavity. Foraging stops during winter months ^[14]. Keep at cool room temperature (around 10-15°C) for 2-3 months.
  • Nesting: Provide small cavities like test tubes, Y-tong nests, or acrylic nests with narrow chambers. They prefer compact, high-ceilinged cavities over thin, flat spaces ^[15]. A test tube setup works well for founding colonies.
• Behavior: Workers are diurnal and forages actively during daylight hours, primarily in spring and early summer ^[14]. They use tandem running to recruit nestmates to food sources ^[16]. These ants are relatively non-aggressive and are known to be poor competitors at food baits ^[17]. They feed on honeydew, plant nectar, seeds, and small insects. Escape prevention is important due to their small size, use fine mesh barriers. Colonies relocate when disturbed or when conditions become unfavorable ^[14].
• Common Issues: tiny size means escapes are likely without fine mesh barriers, colonies often fail during hibernation if kept too wet, queenless colonies are common in the wild, may affect colony stability, slow growth can frustrate beginners who overfeed or overhandle the colony, wild-caught colonies may have parasites that kill them in captivity

Housing and Nest Setup

Temnothorax curvispinosus is a cavity-nesting ant that thrives in small, enclosed spaces. In the wild, they live inside fallen acorns, hickory nuts, hollow twigs, and other natural cavities on the forest floor ^[3]. For captivity, a simple test tube setup works perfectly for founding colonies. As the colony grows, you can upgrade to a Y-tong (AAC) nest or a small acrylic formicarium with narrow chambers. Laboratory studies show they prefer larger cavities with compact, high-ceilinged spaces over thin, flat crevices, even when the total volume is the same ^[15]. This means providing them with chambers that are proportionally deep rather than wide. A small entrance hole leading to a chamber of about 1-2cm works well. Keep the nest area dark or covered, as these ants prefer dim conditions. Escape prevention is critical, use fluon on the edges of any open setups and ensure lid seals are tight, as these tiny ants can squeeze through remarkably small gaps.

Feeding and Diet

In the wild, T. curvispinosus workers forage for honeydew droplets on leaf surfaces, feed at extrafloral nectaries of plants like bracken fern and bigtooth aspen, collect seeds, and scavenge dead insects ^[7]. They do not tend aphids but will readily attend extrafloral nectaries. For captive colonies, offer a constant source of sugar water or honey, and provide small protein sources like fruit flies, pinhead crickets, or other tiny insects. They are not aggressive foragers and are considered poor discoverers of food resources compared to other ant species ^[17], so place food near their nest entrance. Feed protein 2-3 times per week and keep sugar water available at all times. Remove any uneaten prey after 24 hours to prevent mold.

Temperature and Seasonal Care

Keep your colony at room temperature, ideally around 20-24°C. Research shows colony growth optimizes at intermediate temperatures, with the highest growth occurring in warming chambers that are 2-4°C above ambient ^[11]. The minimum temperature for colony growth is around 11.6°C, while the maximum is about 34.1°C, above this, colonies stop growing ^[11]. Their critical thermal maximum (CTmax) is around 43.4°C, but sustained temperatures above 34°C will stress the colony ^[11]. During winter, reduce temperatures to simulate dormancy. Keep them at cool room temperature (10-15°C) for 2-3 months. In the wild, foraging activity is highest in spring and early summer, drops in fall, and stops entirely during winter ^[14]. Do not feed during the winter dormancy period.

Colony Structure and Social Organization

One of the most fascinating aspects of T. curvispinosus is their flexible social structure. Colonies can be either monogyne (single queen) or polygynous (multiple queens), and this can change seasonally ^[5]. Studies show about 36-37% of wild colonies are queenless at any given time, and workers can reproduce in queenright colonies, laying eggs that develop into males ^[18][19]. New colonies are founded through pleometrosis, where multiple queens start a nest together, and new queens can be adopted into existing nests ^[5]. This flexibility makes them robust but also means colony dynamics can be complex. In summer, colonies become polydomous, spreading across multiple nest sites with varying queen numbers, but in winter they coalesce into a single cavity ^[14]. Understanding this can help you interpret behaviors like variable brood production or occasional queenless periods.

Behavior and Observation

Temnothorax curvispinosus is an excellent species for observing complex ant behaviors. They use tandem running to recruit nestmates to food sources or new nest sites, one worker leads another to the target while maintaining physical contact ^[16]. They are also known for their sophisticated house-hunting behavior when colonies need to relocate, using quorum sensing to make collective decisions ^[20]. These ants are diurnal and most active during daylight hours, with foraging peaking in spring and early summer ^[14]. They are relatively non-aggressive and are poor competitors at food baits, often losing to more dominant species ^[17]. Their small size and preference for cavity nesting make them easy to observe in captive setups. Watch for their characteristic long, curved propodeal spines, this is the feature that gives them their scientific name 'curvispinosus' meaning 'curved spine'.

Winter Care and Hibernation

T. curvispinosus requires a winter rest period to maintain healthy colony cycles. In the wild, colonies become less active in fall and stop foraging entirely during winter ^[14]. They overwinter within their nest cavity, typically in a single acorn or nut embedded in leaf litter. About one-third to one-half of all wild nests do not survive the winter, either from colony death or migration to new sites during warm winter days ^[14]. For captive colonies, reduce temperatures to around 10-15°C for 2-3 months during winter. Do not feed during this period. Keep the nest slightly moist but not wet, excessive moisture combined with cool temperatures can be fatal. In spring, gradually warm the colony and resume normal feeding. Queens have about a 50% chance of surviving winter, while workers have roughly 50-67% survival rates ^[14].

Host Species and Parasites

Temnothorax curvispinosus is an important host species for several social parasites, which is worth knowing about if you collect colonies from the wild. It is the preferred host of the slave-making ant Temnothorax duloticus, which raids their colonies to steal brood ^[21][22]. It is also host to Temnothorax americanus and the inquiline parasite Temnothorax minutissimus ^[23][6][24]. If you collect a wild colony and notice unusual ants or behaviors, the colony may be parasitized. Signs include the presence of different-looking ants, suppressed queen reproduction, or workers showing aggression toward what appear to be nestmates. Healthy colonies can sometimes coexist with parasites for some time, but parasitized colonies often decline over time. Purchasing from reputable sellers who verify colony health is recommended if you want to avoid this issue.

Frequently Asked Questions

References