Acromyrmex balzani

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Native to Argentina, Brazil, Paraguay, Peru, Bolivia, and Uruguay ^[1][2]. Found in Cerrado areas, pastures, and grasslands, typically in sunny, open sites with well-drained soil ^[6][5].
• Colony Type: Monogyne (single queen) with polydomous structure, one colony occupies 1-8 physically separate underground subnests that are socially connected. Workers move freely between subnests, but only one subnest houses the queen ^[6][7].
• Size & Growth:
  • Queen: Unknown, not measured in available literature
  • Worker: ~6 mm body length ^[3]
  • Colony: Up to 2832 individuals (including workers and brood) ^[6][7]
  • Growth: Moderate
  • Development: 8-12 weeks (estimated from related species) (Colonies produce brood seasonally. Immature stages are found only in chambers containing the queen, typically in the deepest chambers. The colony cycle alternates between periods with brood and periods with only adults ^[6].)
• Antkeeping:
  • Temperature: 22-26°C. Foraging peaks in late afternoon and evening when temperatures cool, and colonies reduce activity during colder months ^[5].
  • Humidity: Keep nest substrate moderately moist but not waterlogged. They naturally nest in well-drained soils and tolerate drier conditions better than many attines ^[9][10].
  • Diapause: No. As a tropical species, they remain active year-round but naturally reduce activity during cooler, drier seasons ^[6][5].
  • Nesting: Use a naturalistic setup with soil or plaster chambers arranged vertically. Provide 2-5 chambers per subnest, roughly 10-15 cm in diameter, connected by tunnels. Some keepers add a thatched turret at the entrance to mimic their natural nest architecture ^[6][11].
• Behavior: Workers are generally non-aggressive toward keepers but defend their nest if disturbed. They show no aggression toward nestmates from different subnests of the same colony, but attack workers from foreign colonies (94% of encounters resulted in aggression) ^[6]. Foraging is strictly nocturnal, beginning at dusk and peaking between 14:00-15:00 hours in the wild, with workers traveling 2.5-7 meters from the nest ^[5]. They cut grass fragments and carry them along short chemical trails without forming the physical highways seen in Atta species ^[5][12].
• Common Issues: Fungus garden failure is the primary cause of colony death, especially during founding when queens must forage for grass substrate ^[13]., Phorid fly parasitism affects up to 7% of foragers in the wild, keep colonies away from other ant colonies that may carry these parasites ^[10]., Polydomous structure requires more space than single-nest species, provide multiple connected chambers or they will become stressed ^[6]., Low founding success, only about 11% of colonies survive the first year in nature, so expect high mortality with new queens ^[13][17]., External waste disposal requires regular cleaning of the outworld to prevent mold and bacterial growth ^[10].

Housing and Nest Setup

Acromyrmex balzani needs a naturalistic setup with vertical chambers. In the wild, they build 2-5 chambers per subnest, each roughly 10-15 cm wide and 2-13 cm high, arranged vertically and connected by a single tunnel ^[6]. The nest entrance features a distinctive thatched turret made of intermeshed grass fragments, averaging 3 cm high, which may help workers navigate home ^[11][15]. Provide multiple connected chambers to accommodate their polydomous habit, colonies naturally spread into 1-8 subnests ^[6][7]. Use well-drained soil or plaster nests. Keep the fungus chamber moderately moist. The outworld needs space for foraging trails, workers travel 2.5-7 meters in nature ^[5].

Feeding and Fungus Care

Feed only fresh grasses and monocots, they are specialized grass-cutters and reject dicot leaves. Offer Brachiaria decumbens, Brachiaria brizantha, Paspalum notatum, Eleosine indica, or Digitaria insularis ^[5][16]. Cut grass into small fragments (2-5 mm) before offering. Their fungus gardens show high xylanase and pectinase enzyme activity adapted for breaking down grass cell walls, with lower cellulase activity than leaf-cutting species ^[4][16]. The fungus Leucoagaricus gongylophorus is essential, without it, the colony starves. Queens are semi-claustral and must forage to start their garden, making founding risky ^[13]. Remove uneaten grass before it molds.

Temperature and Seasonal Care

Maintain 22-26°C year-round. They are tropical and do not hibernate, though they naturally reduce activity during cooler, drier months (June-September in Brazil) ^[6][5]. Foraging activity peaks in late afternoon and evening, coinciding with temperature drops ^[5]. Avoid temperatures below 18°C or above 30°C. Create a thermal gradient in the nest so workers can choose their preferred temperature.

Colony Structure and Social Organization

Colonies are polydomous, one queen occupies multiple subnests (1-8 typically) that are not physically connected by tunnels but function as one colony through worker movement ^[6][7]. Workers recognize nestmates and show no aggression between subnests of the same colony, but attack foreign workers ^[6]. The queen resides in one subnest, usually the deepest, and brood is only found in chambers containing the queen ^[6]. Workers come in three size classes: small (0.7-1.0 mm head width), medium (1.1-1.8 mm), and large (1.9-3.1 mm), with small workers being most common ^[7].

Reproduction and Nuptial Flights

Nuptial flights occur at dusk (around 19:25-19:44), typically during light rain in spring and early summer (September-October in Brazil) ^[13]. Males form leks (aggregations) over vegetation, averaging 33 males per site, and compete intensely for females, about 4 males per female in mating balls ^[13]. Copulation lasts roughly 18 minutes, after which the male's genital capsule detaches and remains in the female until she removes it with her mandibles ^[13]. Females break their own wings within a minute of landing and dig a founding chamber less than 30 cm deep. They forage for grass substrate and do not close their nest entrance during founding ^[13].

Common Problems and Health Issues

Fungus garden failure kills colonies, especially during founding when queens must balance foraging with nest maintenance ^[13]. Phorid flies (Apocephalus species) parasitize workers, with larvae developing in the thorax and emerging after 15-18 days, maintain clean conditions to reduce fly attraction ^[10]. Colonies have naturally high mortality, only 34 of 296 founded colonies survived one year in field studies ^[17]. External waste piles can harbor pathogens, clean these regularly ^[10]. If the fungus turns dark or workers avoid the garden, check humidity and temperature immediately.

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