Tetramorium immigrans - "Pavement Ant"
Tetramorium immigrans, commonly known as the Pavement Ant, is a small, adaptable ant species frequently encountered in urban and suburban environments. These ants are typically dark brown to black, sometimes with a reddish tint on their legs and antennae, and their bodies are covered with fine, sparse hairs that give them a slightly velvety appearance. Workers usually measure between 2.5 to 4 millimeters, while queens are larger, ranging from 6 to 8 millimeters. They are known for their scavenging habits and can be quite active, making them engaging to observe.
- Difficulty: Easy
- Origin & Habitat: Europe and the Caucasus Mountains, widely introduced to North and South America. in Urban and semi-urban areas, often nesting in cracks of pavement, sidewalks, building foundations, under rocks, wood, and in lawns..
- Colony Type: Monogyne (single queen), claustral (queen seals herself in) founding.
- Size & Growth:
- Queen: 6-8mm
- Worker: 2.5-4mm
- Colony: Large (thousands to tens of thousands). Fast, with colonies potentially reaching over 1000 workers in a year if heated and well-fed. growth.
- Antkeeping:
- Temperature: Preferred temperature range is 21-29°C (70-85°F), with a gradient recommended to allow the ants to choose their ideal spot for brood development and general activity..
- Humidity: Brood prefers high humidity, while workers prefer medium humidity. A humidity gradient within the nest is highly recommended, allowing the ants to move eggs and larvae closer to moisture and pupae slightly away from the most humid areas..
- Diapause: Not required. 2-3 months at 4-10°C.
- Nesting: Pavement Ants are adaptable and can thrive in various well-made formicariums that offer humidity. They are not picky and will accept most nests that maintain proper humidity. Test tube setups are suitable for founding..
- Behavior: Medium (towards food or other ants) aggressiveness.
- Common Issues: Workers drowning in honey/sugar water, Food molding in nest/outworld, Colony stalling due to insufficient heat/food, Humidity fluctuations, Escape artists (due to small size), Misidentification with similar species.
Pavement Ants are incredibly robust and forgiving, making them an excellent choice for beginner ant keepers. Their adaptability means they can thrive in a variety of setups, provided their basic needs for heat, humidity, and food are met. While they can grow quickly, consistent feeding of both protein and sugars is key to optimizing their colony expansion. Pay close attention to their foraging behavior; a thriving colony will be actively seeking out food, indicating they're well-provisioned.
One interesting characteristic of Tetramorium immigrans is their feeding versatility. They are true generalists, accepting a wide array of food items, from various feeder insects like mealworms and fruit flies to honey, sugar water, and even some seeds and artificial proteins. This broad diet makes feeding them relatively easy. However, it's worth noting that providing a varied protein diet can significantly boost the queen's egg production, leading to even faster colony growth.
Although typically monogynous, Pavement Ants can exhibit temporary pleometrosis during the founding stage, where multiple queens start a colony together. However, once the first workers (nanitics) arrive, they will almost certainly reduce the queen count to a single dominant queen. Therefore, while it might seem appealing to start with multiple queens for a larger initial brood, it's generally not recommended for long-term multi-queen colonies.
While diapause (hibernation) is optional for Tetramorium immigrans and many keepers choose to skip it without negative side effects, providing a short diapause period can contribute to the long-term health and longevity of the colony. If you opt for diapause, ensure they have a constant water source and are kept in a cool, dark place above freezing temperatures.
These ants are known for their territorial battles in the wild, especially during late spring and early summer, where large groups from different colonies might engage in impressive sidewalk skirmishes. While they are generally not aggressive towards humans and their sting is mild and rarely used, their active and sometimes aggressive foraging behavior towards food and other ants makes them a dynamic species to observe in a formicarium.
