Myrmecia infima

Myrmecia infima

Myrmecia infima is a small bull-dog ant native to Western Australia, found along the coast from Geraldton to Albany, including Rottnest Island ^[1]. Workers are tiny compared to most Myrmecia species, the name 'infima' literally means 'lowest' or 'least', reflecting their diminutive size. They have the typical bull-dog ant appearance: powerful mandibles, large eyes, and a distinctive stinger. These ants are rarely encountered because their nests have never been discovered in the wild, workers are typically found foraging on flowers and foliage rather than near their nests ^[1]. The taxonomy of this species is problematic within the M. urens group, making identification challenging ^[1].

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Western Australia, found along the coast from Geraldton to Albany, including Rottnest Island. They forage on flowers and foliage in Mediterranean climate areas ^[1].
• Colony Type: Likely single-queen colonies based on typical Myrmecia patterns, though colony structure has not been documented.
  • Colony: Monogyne
  • Founding: Claustral
• Size & Growth:
  • Queen: Estimated 12-15mm based on small Myrmecia species
  • Worker: Estimated 6-8mm, smaller than typical Myrmecia
  • Colony: Unknown, likely smaller colonies than larger Myrmecia species
  • Growth: Moderate, estimated based on related species
  • Development: Estimated 8-12 weeks based on genus patterns (Development time inferred from related Myrmecia species, specific data unavailable)
• Antkeeping:
  • Temperature: Keep around 22-26°C, Mediterranean climate suggests moderate warmth. A gentle gradient allows ants to self-regulate.
  • Humidity: Moderate humidity around 50-60%. Provide a water tube and occasional misting of the outworld.
  • Diapause: Likely, Western Australian winters are mild but distinct. Provide a cool period around 10-15°C for 2-3 months.
  • Nesting: Y-tong or acrylic nests work well. Provide moist substrate for brood chambers. Natural setups with soil and stones also suitable.
• Behavior: Bull-dog ants are known for their aggressive temperament and painful stings. M. infima will defend the nest vigorously and has a potent sting, handle with caution. They are active foragers, hunting insects and collecting nectar from flowers. Escape risk is moderate due to their small size but they are not strong climbers like some ants. Use standard barrier methods like Fluon on test tube rims.
• Common Issues: stings are painful, use caution when servicing the colony, nesting behavior is poorly understood, may have unusual chamber preferences, small colony size means slower population growth and less resilience, wild-caught colonies may be difficult to establish, taxonomic uncertainty means you may not have true M. infima

Appearance and Identification

Myrmecia infima is one of the smallest species in the genus Myrmecia. Workers are estimated at 6-8mm, making them significantly smaller than most bull-dog ants which typically reach 10-15mm. The species belongs to the M. urens group, a collection of small bull-dog ants that are difficult to distinguish from one another morphologically. The taxonomy within this group is problematic, M. infima was originally described from Perth, and some researchers believe M. nigra from East Fremantle may be the same species. Coloration is typically dark with some yellowish or reddish markings on the gaster. Queens are larger than workers (estimated 12-15mm) and winged during the founding stage. Males have been described but are rarely encountered ^[1].

Natural History and Foraging

What makes M. infima unusual is that despite being known for over a century, no one has ever found a nest in the wild. Workers have been collected by sweeping flowers and foliage, they are active foragers on plants, likely hunting small insects and collecting nectar. This is unusual because most Myrmecia species nest in soil or under stones with obvious nest entrances. The species has been recorded from Geraldton, King's Park Perth, Margaret River, and Rottnest Island along the Western Australian coast ^[1]. They appear to be active during the warmer months, typical of Mediterranean climate patterns. The fact that nests have never been found suggests they may nest in concealed locations like rotting wood, under bark, or in rock crevices.

Housing and Nest Setup

For captive care, a Y-tong (AAC) nest or acrylic formicarium works well for these small bull-dog ants. Provide a water tube attached to the nest for humidity. Because their natural nesting preferences are unknown, offer options: a section of moist soil or sand in one area, and dry chambers in another. This lets the colony choose. The outworld should be escape-proof, while not strong climbers, they are agile. Use Fluon on test tube rims or formicarium connections. A foraging area of at least 10x10cm allows space for hunting and food storage. Lighting is not critical, but they are diurnal and more active with a day/night cycle.

Feeding and Diet

Like other Myrmecia species, M. infima is a generalist predator and scavenger. Feed small insects like fruit flies, small crickets, and mealworms. They will also accept sugar water or honey as an energy source. In the wild, their flower-visiting behavior suggests they may collect nectar, so sugar sources are likely accepted. Offer protein foods 2-3 times per week, and keep a sugar source available at all times. Remove uneaten prey after 24 hours to prevent mold. Because workers are small, prey items should be appropriately sized, no larger than the ant's head.

Temperature and Seasonal Care

Maintain temperatures around 22-26°C during the active season. Western Australia's climate is Mediterranean, warm, dry summers and mild, wet winters. During winter (roughly June-August in the Southern Hemisphere), reduce temperature to 10-15°C to simulate their natural seasonal cycle. This diapause period helps synchronize colony activity and may be important for reproductive development. Do not feed heavily during the cool period, the colony will be less active and metabolic rates are reduced. Return to normal temperatures gradually in spring.

Safety and Handling

All Myrmecia ants have potent stings, and M. infima is no exception. Despite their small size, they can deliver a painful sting comparable to larger bull-dog ants. They are defensive of their nest and will attack perceived threats. When servicing the colony, work carefully and avoid disturbing the nest directly. If attacked, the sting can cause localized pain and swelling for several hours. People with insect venom allergies should exercise extreme caution. Use red light or work quickly when the colony is active to minimize disturbance. ^[1]

Frequently Asked Questions

References