Formica truncorum
Temperature
18–24 °C
Humidity
50–70%
Colony size
20,000–200,000
Queen size
9–11 mm
Worker size
4.5–9 mm
Hibernation temp
5 °C
Diet
Care Guide
Formica truncorum is a fascinating and challenging species for experienced ant keepers, belonging to the group of social-parasitic ants. This means that a newly mated queen cannot start her own colony independently; instead, she must infiltrate a host colony—typically of another *Formica* species—kill or displace the resident queen, and take over the existing workforce. Once established, the colony grows rapidly, eventually reaching tens of thousands to over a hundred thousand workers. The queen measures between 9 and 11 mm, while workers show a noticeable size range from 4.5 to 9 mm, though they do not exhibit the extreme polymorphism seen in some other genera. These ants are vigorous foragers, collecting insects, sugary liquids, and honeydew from aphids, and they have a strong need for protein to sustain their large brood.
Care difficulty
Keeping *Formica truncorum* is classified as advanced, primarily because of their parasitic founding behavior. Successfully establishing a colony typically requires providing a queen with a suitable host colony or acquiring a colony that has already overcome this stage. Even after establishment, the ants demand consistent attention: they require a protein-rich diet, regular feeding, and proper hibernation conditions. Their sensitivity to stress and large colony size in the later stages add to the challenge. This species is not recommended for beginners, but for keepers who have already mastered more straightforward species and are ready for the intricacies of parasitic ants.
Housing
A formicarium for *Formica truncorum* should offer ample space for a rapidly growing population, with a dry nesting area and a separate foraging zone. Temperature should be kept in the range of 18–24°C, and humidity within 50–70%—higher moisture in the brood chambers but drier areas for the workers to rest. These ants are active and need a foraging arena with a secure lid, as they can become escape artists. Hibernation is mandatory: from late autumn through winter, the colony must be gradually cooled to around 5°C for several months. During this period, reduce feeding but ensure some humidity remains to prevent desiccation. Providing a steady source of protein, such as insect feeders or meat-based foods, alongside sugar water or honeydew, is essential for brood development and colony growth.
First days after purchase
Upon receiving your *Formica truncorum* colony or queen (with host workers), place the formicarium in a quiet, dimly lit location and allow the ants to settle for at least 24–48 hours with minimal disturbance. Ensure they have immediate access to water via a moistened cotton ball or test tube, and offer a small amount of sugar water and a tiny piece of insect protein. Observe carefully over the first week: if the queen is present and workers are tending to her and the brood, the colony is adjusting well. Avoid unnecessary vibrations or light exposure, as these ants are easily stressed during the acclimation period. Once they begin foraging actively, you can gradually introduce regular feeding and clean any leftover food to prevent mold.