Temnothorax nylanderi (The European Acorn Ant)

Temnothorax nylanderi is a classic and beloved representative of the European ant fauna. Known as the European Acorn Ant, this diminutive species is a master of living in small spaces, specifically inside the hollowed-out remains of acorns, hazelnuts, and small twigs on the forest floor. Found across much of temperate Europe and parts of North Africa, Temnothorax nylanderi is a quintessential "low-maintenance" species for the ant keeper. They are peaceful, meticulously clean, and exhibit fascinating social behaviors—like tandem running—all within a colony that remains compact enough to fit inside a single nut for its entire existence.

Natural History and Identification

Temnothorax nylanderi is a very small ant, with workers typically measuring between 2.3mm and 3.5mm in length. Their coloration is a beautiful, warm yellowish-orange to a light brownish-yellow, often with a slightly darker, brownish band on the first segment of the gaster. Like its North American relatives, it has a pair of sharp spines on the back of its thorax (the propodeum). They have a smooth, glossy appearance and a very deliberate, methodical way of moving that makes them easy to observe even without high magnification.

The queens are only slightly larger than the workers, typically ranging from 3.5mm to 4.5mm. They share the same golden-orange coloration and are often seen moving gracefully among their workers and brood. One of the most interesting aspects of the genus Temnothorax is the long lifespan of the queens; despite their small size, a queen can live for over a decade in a stable environment. The colony is monomorphic, meaning all workers are of a similar size and shape, which reflects their specialized lifestyle in confined spaces.

Distribution and Native Habitat

This species is native to Europe and is widely distributed from the British Isles and Scandinavia down to the Mediterranean and into North Africa. They are strictly forest dwellers, preferring deciduous and mixed woodlands where there is a thick layer of leaf litter and a consistent supply of fallen nuts. They are particularly abundant in oak forests, where the abundance of acorns provides them with an endless supply of potential nesting sites.

Their nesting habits are highly specialized. Temnothorax nylanderi is an "obligate" cavity nester. Their primary choice of home is a hollow acorn or hazelnut that has been vacated by a weevil or other insect. They are also known to nest in small hollow twigs, galls, or even in the crevices of bark on standing trees. Because they live in such small, pre-made cavities, their nests are exceptionally secure and easy for the ants to defend against larger predators.

Diet and Foraging Behavior

Temnothorax nylanderi is a generalist scavenger and opportunistic forager with a very peaceful demeanor. They do not form large trails; instead, individual workers or small groups forage independently, searching the leaf litter for small dead insects, organic debris, and floral nectar. They are also known to collect "honeydew" from aphids on low-growing plants. Because they are so small and non-aggressive, they often forage in the same areas as much larger and more aggressive ant species without causing conflict.

In captivity, they are exceptionally easy to feed. Because their colonies remain small (rarely exceeding 200 workers), they require very little food. A single fruit fly or a small drop of honey-water can sustain a colony for several days. They are very clean ants and will often create a small "refuse pile" at the far end of their outworld. They are not picky eaters and will accept a variety of proteins and sugars. Watching them communicate through subtle chemical signals and antennation is one of the joys of keeping this species.

Colony Lifecycle and Social Structure

The lifecycle of Temnothorax nylanderi begins with the nuptial flights, which typically take place in mid-summer (July and August) on warm, humid afternoons. The queens are fully claustral founders and will seek out a small wooden cavity or an empty nut to begin their first brood. One of the most interesting aspects of Temnothorax is the behavior called "tandem running." When a worker finds a new food source or a better nesting site, she will lead a nestmate to the location in a coordinated line, with the follower keeping its antennae in constant contact with the leader's gaster.

Their social structure is generally monogynous (having one queen), though some populations may exhibit occasional polygyny. A mature colony rarely exceeds 100 to 150 workers. This small size is an adaptation to their limited nesting space. Interestingly, Temnothorax nylanderi is a common host for certain parasitic ants, like Temnothorax ravouxi, which will infiltrate the nest and replace the nylanderi queen, turning the workers into "slaves" to raise its own offspring.

Ant Keeping: Care and Housing

Temnothorax nylanderi is widely considered one of the best species for beginner ant keepers, as well as for those who live in smaller spaces. They are exceptionally hardy, take up very little room, and are completely non-aggressive. They prefer temperatures between 20°C and 24°C during their active season. While they are more tolerant of lower humidity than subterranean species, they still require a consistent water source and a localized area of higher humidity within the nest for the health of the brood.

Hibernation is a requirement for this temperate species, with a 3-4 month period at temperatures between 5°C and 10°C. One of the highlights of keeping European Acorn Ants is that you can provide them with "natural" nesting sites like cleaned-out acorns or small hollow twigs, which they will quickly move into. They are also highly resistant to stress and are not easily disturbed by light or vibrations, making them perfect for close observation on a desk or bookshelf.

Recommended Setup

Because they are tiny and live in small cavities, the All-in-One setup is a fantastic choice for both founding and established colonies. It provides a compact and secure environment that is perfectly scaled to their needs. For those who want a more permanent and aesthetically pleasing home, the Paris formicarium is highly recommended. The Paris nest's material is excellent for maintaining the humidity levels these ants need, and its structured chambers provide the perfect "cavity-like" feel that Acorn Ants love. The excellent visibility of the Paris nest ensures you can see every detail of their tandem running and social interactions. Even a mature colony of Temnothorax nylanderi will thrive in the Paris nest for many years.

Fun Facts and Advanced Observations

• The "Tandem Run" Communication: Tandem running is one of the most studied behaviors in myrmecology, and Temnothorax nylanderi is the model species for understanding how ants "teach" one another.
• Nut Dwellers: In the wild, you can sometimes find multiple acorns on the forest floor, each containing a completely different colony of Temnothorax nylanderi, showing how high their nesting density can be.
• Long-Lived Monarchs: A queen of this species can live for 10-15 years, meaning a single small colony can be a companion for a significant portion of a keeper's life.
• Slave-Making Victims: In some regions, a large percentage of Temnothorax nylanderi colonies are actually "mixed" colonies, having been raided and enslaved by parasitic species.