Messor mcarthuri

Messor mcarthuri

Messor mcarthuri is a large harvester ant species native to Greece, Turkey, and Bulgaria, recently described in 2018. Workers have a distinctive appearance with brown to brownish-red heads and mesosoma, dark brown abdomen, and a unique regular costate (ridged) sculpture covering their entire body including the petiole. Major workers can appear entirely dark brown. They have abundant erect hairs on the sides of their head and a short, flattened first funicular segment. This species belongs to the Messor structor species group and was named in honor of ant taxonomist Archie J. McArthur. Unlike many harvester ants, M. mcarthuri colonies on Crete have been documented as polygynous, meaning they contain multiple queens. These ants are commonly found nesting under stones in open habitats ranging from arid pastures to humid stream valleys.

Quick Summary

• Difficulty: Easy
• Origin & Habitat: Greece, Turkey, and Bulgaria. Found in various open habitats including pastures, stone hills, roadsides, oak forest edges, olive plantations, and limestone gorges up to 820m elevation ^[1][2].
• Colony Type: Polygynous (multiple queens per colony), confirmed on Crete ^[2]. Single-queen colonies may also be possible.
  • Colony: Polygyne
  • Founding: Claustral
• Size & Growth:
  • Queen: Large, similar in size to M. muticus, M. ponticus and M. structor ^[3]
  • Worker: Large, similar to M. ponticus, usually larger than M. ibericus, M. muticus, and M. structor ^[3]
  • Colony: Unknown maximum, but polygynous colonies can grow substantial
  • Growth: Moderate, typical for Messor genus
  • Development: Estimated 6-10 weeks based on genus patterns (Development time follows typical Messor patterns, exact timeline unconfirmed for this species)
• Antkeeping:
  • Temperature: Keep at room temperature (20-25°C). They tolerate a range from cool to warm conditions, matching their Mediterranean habitat ^[1]
  • Humidity: Moderate, they nest under stones in both arid and humid areas. Keep nest substrate moderately moist but allow some drying between waterings ^[2]
  • Diapause: Yes, as a Mediterranean species, they likely require a winter rest period. Reduce temperature to 10-15°C for 2-3 months during winter.
  • Nesting: Nests under stones in captivity. Use a naturalistic setup with flat stones or a Y-tong/plaster nest with chambers sized for their large body size. They do well in dry to moderately humid conditions.
• Behavior: Harvester ants that collect and store seeds as their primary food source. Workers are active foragers that search for seeds and other organic matter. They are not aggressive and rarely sting. Colonies are polygynous with multiple queens. Escape risk is moderate, their large size makes them easier to contain than tiny ants, but they can still climb smooth surfaces.
• Common Issues: seed storage mold, keep seeds dry and remove uneaten seeds regularly to prevent fungal growth, polygynous colonies may have queen conflicts during establishment, monitor for aggression, hibernation failure, colonies that don't receive proper winter rest may have reduced longevity, overheating, despite being Mediterranean, extreme heat can stress colonies, colonies may abandon chambers if conditions are too wet, provide dry resting areas

Housing and Nest Setup

Messor mcarthuri does well in naturalistic setups that mimic their natural nesting preferences. In the wild, they nest under stones in open habitats, so flat stones placed on sandy soil work excellently. You can also use Y-tong (acrylic) nests or plaster nests with chambers sized appropriately for their large worker size. Provide a foraging area with a sand or soil substrate where they can search for seeds. Because they are polygynous (multiple queens), you don't need to separate queens during founding if you're starting with an established colony. For founding colonies, a test tube setup works well until the colony reaches 20-30 workers, then move to a formicarium. Ensure the nest has both humid chambers for brood and drier areas for seed storage. ^[1][2]

Feeding and Diet

As harvester ants, Messor mcarthuri primarily collects and stores seeds. Provide a variety of seeds including grass seeds, bird seed mix, and millets. They will also accept protein sources like small insects (fruit flies, small crickets, mealworms) and can be fed sugar water or honey occasionally. Unlike some harvester ants that rely heavily on seeds, they do accept protein and will forage for it. Remove uneaten seeds regularly to prevent mold. Fresh water should always be available. Their large size means they can handle larger seeds than tiny ant species. ^[2][1]

Temperature and Seasonal Care

These Mediterranean ants thrive at room temperature (20-25°C) and can tolerate temperatures from 15°C to 30°C. They do not require heating in most homes. During winter, provide a diapause (hibernation) period of 2-3 months at 10-15°C. This mimics their natural seasonal cycle and helps maintain colony health. Reduce feeding during winter and keep the nest slightly drier. In summer, ensure they have access to fresh water and avoid placing the colony in direct sunlight that could cause overheating. Their native range includes both cool highland areas and warm lowlands, giving them flexibility. ^[1]

Colony Structure and Growth

Messor mcarthuri is polygynous, meaning colonies naturally have multiple queens. On Crete, researchers have documented colonies with multiple reproductive queens ^[2]. This is unusual compared to many ant species and means your colony may have better survival odds, if one queen dies, others can continue reproducing. Growth is moderate, expect the first workers (nanitics) within 6-10 weeks after founding, then steady growth over several months. Large colonies can contain thousands of workers. The species is large-bodied, so their chambers should be appropriately sized. Major workers (larger individuals) develop as the colony grows and help with seed processing.

Behavior and Foraging

These are typical harvester ants with active foraging behavior. Workers venture out to collect seeds and bring them back to the nest for storage. They are not particularly aggressive and will flee rather than attack when disturbed. Their large size makes them easy to observe. Colonies establish multiple entrance holes and maintain clear foraging trails. You may observe workers returning with seeds held overhead in their mandibles, a classic harvester ant behavior. They are primarily diurnal, most active during daylight hours. The polygynous colony structure means you may see multiple queens in the nest without aggression between them. ^[1][2]

Frequently Asked Questions

References