Myrmica ruginodis (The Rough-knotted Red Ant)

Myrmica ruginodis is a classic representative of the European and Palearctic ant fauna. Often overshadowed by its close relative, Myrmica rubra, this species is nonetheless one of the most common and ecologically significant ants in temperate forests, moors, and gardens. Known for its rich reddish-brown color, its painful sting, and its preference for cool, damp environments, Myrmica ruginodis is a fascinating species for the ant keeper who appreciates the "sting-capable" subfamily Myrmicinae. Unlike many of the more "hyper-active" ants, Myrmica ruginodis has a more methodical, deliberate pace of life, making it an excellent subject for detailed observation.

Natural History and Identification

Myrmica ruginodis is a medium-sized ant, with workers typically measuring between 4.0mm and 6.0mm. Their coloration ranges from a light ginger-red to a deep, dark mahogany. The most striking feature of the genus Myrmica is the "two-node" waist (petiole and post-petiole) and the presence of two sharp spines on the back of the thorax (propodeum). To distinguish ruginodis from other Myrmica, specialists look at the "scape" (the long first segment of the antenna), which in ruginodis is gently curved at the base rather than sharply angled.

The queens are only slightly larger than the workers, typically ranging from 6mm to 7.5mm. This small size difference between castes is a hallmark of the genus. Interestingly, Myrmica ruginodis exists in two distinct forms: "macrogyna" (large queens) and "microgyna" (small queens). The macrogyna form tends to found colonies independently, while the microgyna form is often parasitic on existing colonies of the same species. Males are dark, almost black, and are significantly more slender than the queens.

Distribution and Native Habitat

This species is widely distributed across Europe and Northern Asia. It is particularly common in the United Kingdom, Scandinavia, and the cooler regions of central Europe. Myrmica ruginodis is much more of a woodland specialist than Myrmica rubra. It prefers damp, shaded environments such as forest floors, deciduous woodlands, and the edges of bogs. However, it is also a frequent inhabitant of domestic gardens, especially those with plenty of leaf litter, mulch, and shaded corners.

Their nests are typically found in moist soil, under stones, or within rotting wood. They are also known to nest in clumps of moss or in the "tussocks" of grass in moorlands. Unlike the deep subterranean nests of Lasius, Myrmica nests are often quite shallow, which makes them very sensitive to changes in surface temperature and humidity.

Diet and Foraging Behavior

Myrmica ruginodis is an opportunistic omnivore. They are effective hunters of small soil invertebrates, such as springtails, mites, and small larvae. They also scavenge for dead insects and organic matter. One of their primary food sources is honeydew, and they will readily climb vegetation to tend to aphids. Their foraging style is slow and methodical; they "patrol" the ground with their antennae constantly sweeping the surface for chemical cues.

In captivity, they are reliable feeders. They enjoy a variety of proteins, including chopped-up mealworms and crickets. They are particularly fond of liquid sugars, and a constant supply of honey-water or sugar-water is essential. Because they are adapted to damp woodland floors, they are very sensitive to hunger and desiccation, so they should be fed regularly. Unlike some other ants, they don't store large amounts of food in the nest, so they need a consistent intake.

Colony Lifecycle and Social Structure

The lifecycle of Myrmica ruginodis is marked by the mid-to-late summer nuptial flights, which typically occur in August. These flights are often smaller and more localized than the massive swarms of Lasius species. After mating, the queens of the "macrogyna" form are semi-claustral founders. This means that while she starts her nest in a small chamber, she must occasionally venture out to forage for food to supplement her energy reserves while raising her first brood. This is a critical distinction for the ant keeper, as a founding Myrmica queen requires a small outworld or "foraging box" even before her first workers arrive.

Colonies of Myrmica ruginodis are often polygynous, meaning they can contain multiple queens. This allows the colony to reach a substantial size, sometimes exceeding 2,000 to 3,000 workers. The multiple queens also provide a high degree of resilience, as the colony can continue to function even if one queen dies.

Ant Keeping: Care and Housing

Myrmica ruginodis is a rewarding species for those who can provide the right environmental conditions. The most important factor is moisture. They are highly intolerant of dry conditions and will quickly perish if the nest dries out. The temperature should be kept relatively cool, ideally between 18°C and 22°C. They do not enjoy high heat and can be severely stressed by temperatures above 25°C.

Hibernation is mandatory for this temperate species. They should be kept at 4°C to 8°C for 4-5 months. Because they are often found in rotting wood or under moss, they appreciate a nesting environment that feels "organic." For the ant keeper, this means providing a setup that can maintain high humidity while also allowing for good air circulation to prevent mold growth.

Recommended Setup

The All-in-One kit is an excellent choice for starting with Myrmica ruginodis, especially for semi-claustral queens that need easy access to food during the founding stage. The integrated design makes it easy to maintain the high humidity levels they require. For larger, established colonies, the Paris formicarium is highly recommended. The Paris nest's material is perfect for maintaining the damp, "earthy" feel that Myrmica crave. The Large Habitat Kit can also be used for a more naturalistic setup, but keepers must be careful to ensure that the soil or substrate remains consistently moist throughout the entire nest area.

Fun Facts and Advanced Observations

• The "Musical" Ant: Myrmica species are known for their ability to produce sounds through "stridulation." By rubbing a small scraper on their waist against a series of ridges on their abdomen, they can produce a faint squeaking sound, which is used for communication within the nest.
• A Potent Sting: While they are generally not aggressive unless their nest is disturbed, Myrmica ruginodis possesses a functional sting. The sensation is often compared to a nettle sting—a sharp, burning pain followed by a small, itchy bump.
• Semi-Claustral Founding: Observing a founding Myrmica queen is a unique experience, as you get to see her act as both a hunter and a mother, a behavior that is lost in the more "advanced" fully claustral species.
• Microgynes vs. Macrogynes: The existence of two queen forms in the same species is a fascinating evolutionary puzzle. The smaller microgynes are essentially "social parasites" within their own species, relying on the larger macrogynes to do the heavy lifting of colony establishment.