Acromyrmex octospinosus

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Neotropical region from Mexico to Brazil, including Cuba, Trinidad, and the Caribbean islands, found in tropical forests, pastures, agricultural areas, and disturbed sites ^[1][2][10]
• Colony Type: Facultatively polygynous, most colonies have a single queen, but some populations contain multiple queens, queens are highly polyandrous, mating with 4-10 males ^[2][11][12]
• Size & Growth:
  • Queen: Approximately 8-9mm total length ^[4]
  • Worker: Highly polymorphic: minors 2-4mm, media 4-7mm, majors 7-10mm ^[3]
  • Colony: Up to 40,000 workers in mature colonies ^[3][13]
  • Growth: Slow, colonies take years to reach maximum size
  • Development: Approximately 60 days (8-9 weeks) at 25°C ^[3] (Development time depends on temperature, majors take longer to develop than minors. Foundresses produce 3-7 workers in approximately 3 months ^[14])
• Antkeeping:
  • Temperature: Keep at 25-28°C year-round, use heating cables to maintain tropical conditions ^[5][15]
  • Humidity: High humidity 70-80% with good ventilation to prevent mold, nest substrate should remain moist but not waterlogged ^[5][15]
  • Diapause: No, tropical species active year-round, do not hibernate ^[1]
  • Nesting: Large formicarium required with dedicated fungus garden chamber, naturalistic soil or plaster nests work best, they use roots as platforms to suspend fungus gardens in the wild ^[14][6]
• Behavior: Active foragers that cut leaves and flowers, polymorphic workers with division of labor where minors tend the fungus garden and majors forage and defend, can be aggressive when disturbed, require large foraging areas ^[3][16]
• Common Issues: fungus garden failure from incorrect humidity, temperature, or contaminated plant material is the primary cause of colony death, mold outbreaks in the nest from poor ventilation or excessive moisture, insufficient food supply, require constant fresh leaves, colony will decline rapidly without fresh vegetation, escapes, large workers can chew through soft materials and climb smooth surfaces, slow initial growth, first workers take approximately 3 months to emerge and colony builds slowly, invasive species, not legal to keep in some regions where it is established

Fungus Garden Maintenance

The fungus garden is the heart of the colony and requires precise conditions to survive. You must provide a constant supply of fresh plant material, typically leaves from bramble, privet, oak, or fruit tree leaves work well in captivity ^[5][15]. The ants chew the leaves into pulp and mix them with fecal fluid containing fungal enzymes to create the garden substrate ^[17]. Maintain high humidity around 70-80% but ensure adequate ventilation to prevent mold growth ^[5]. The garden should be kept in a dark chamber as light stresses the fungus. Remove any moldy or contaminated garden material immediately, as the parasitic fungus Escovopsis can destroy the garden and kill the colony ^[7]. Never use pesticides on plants fed to the colony, as residues will kill the symbiotic fungus. The fungal symbiont produces specialized gongylidia (swollen hyphal tips) that are the primary food for the ants ^[5].

Nest Preferences and Setup

In nature, Acromyrmex octospinosus nests underground in soil cavities, often using tree roots as platforms to suspend the fungus garden above the chamber floor ^[14]. They may also nest in rotting wood or occasionally in arboreal situations in some regions ^[6]. For captive colonies, provide a large formicarium with at least two distinct chambers: one for the fungus garden and one for waste disposal. The fungus chamber should be dark, humid, and spacious enough to accommodate a growing garden ^[1]. Use plaster, gypsum, or naturalistic soil mixes that retain moisture without becoming soggy. Include a foraging area or outworld where workers can process leaves before bringing them to the garden. Foundresses in the wild attach their gardens to living rootlets, suspending them above the earthen chamber floor ^[14].

Feeding and Diet

These ants do not eat the leaves directly, they feed the leaves to their fungus garden and consume the fungal growth (gongylidia) ^[5]. Offer fresh leaves 3-4 times per week, removing old dried material before it molds. They accept a wide variety of plant material including bramble, privet, rose petals, oak leaves, and small amounts of fruit ^[15][5]. They also collect flowers and fallen plant material in the wild ^[6]. Do not offer protein sources like insects, the fungus provides all necessary nutrition. Provide water via test tubes or moist cotton in the outworld, but never let water directly contact the fungus garden as this causes drowning and rot. Workers also ingest plant sap directly while cutting leaves ^[18].

Temperature and Seasonal Care

As a tropical species, Acromyrmex octospinosus requires warm temperatures year-round with no diapause ^[1]. Maintain the nest at 25-28°C using heating cables or mats placed on one side of the nest to create a gradient ^[5][15]. Temperatures below 20°C will slow fungus growth and brood development significantly. Humidity should remain high at 70-80%, but stagnant air promotes mold, so ensure gentle ventilation ^[5]. Monitor the fungus garden surface, if it dries out, increase humidity, if condensation forms heavily, increase ventilation. In the wild, they often inhabit relatively disturbed, drier sites ^[19].

Colony Founding and Growth

Queens are semi-claustral, meaning they must leave the nest to forage for plant material during the founding stage ^[14][20]. In nature, foundresses use tree roots as platforms for their initial fungus garden and produce 3-7 workers in approximately 3 months ^[14]. Captive founding is extremely difficult and rarely successful, most keepers start with established colonies. Growth is slow initially but accelerates once the colony reaches several hundred workers. Full colonies may contain 10,000-40,000 workers after several years ^[3][13]. Queens mate with multiple males (polyandrous), creating genetically diverse worker offspring ^[16]. Colony foundation is primarily haplometrotic with 99% of nests founded by a single queen, though pleometrosis (multiple founding queens) occurs in about 1-3.5% of cases ^[14].

Defense and Symbiotic Partners

These ants possess multiple defense systems. Workers have metapleural glands that secrete antibiotic compounds including indoleacetic acid to prevent pathogen growth ^[21]. They also host Pseudonocardia bacteria on their cuticle that produce antifungal compounds like nystatin to protect against Escovopsis garden parasites ^[7]. Mature workers develop a unique biomineral armor of high-magnesium calcite that hardens their cuticle and improves survival in combat with other ants ^[22]. Major workers (7-10mm) defend the nest and forage, while smaller workers tend the garden and brood ^[3]. The bacterial symbionts are vertically transmitted on the cuticle of gynes during mating flights ^[23]. Workers also practice waste management, disposing of old garden material and debris in separate chambers to prevent disease spread ^[24].

Frequently Asked Questions

Report an Issue

The current care sheet is based fully on literature. See inconsistencies, or something that's incorrect? Please report here, it will be resolved after review from an admin. Contributing to the blogs tab also helps providing information, to make us be able to further improve the caresheets. Thank you for your support!

References