Ants are common insects, actively foraging during warmer months. As temperatures drop, they seem to disappear. This seasonal absence doesn’t mean they’ve died off; instead, ants employ strategies to survive the cold, ensuring colony continuity until conditions improve.
Ants’ Winter Retreat
As temperatures decline, ants, being ectothermic, seek stable, insulated shelters. They typically retreat deep underground into established nests, often burrowing several feet below the frost line. Here, soil provides a consistent temperature above freezing. Some species also find refuge in natural spots like beneath rocks, under tree bark, or within wood structures. These locations provide essential winter shelter.
Once in their winter refuges, ants enter diapause, a period of suspended development or reduced metabolic activity. Unlike true mammalian hibernation, ants in diapause are not entirely unresponsive but significantly slow their movements and activity. This adjustment conserves energy, allowing them to survive on minimal resources when food is scarce and foraging conditions are unsuitable.
Physiological Adaptations for Cold Survival
To withstand freezing temperatures, ants have evolved biological mechanisms. Many species produce natural “antifreeze” compounds, primarily glycerol, which lowers the freezing point of their hemolymph. This prevents ice crystal formation within cells, which would otherwise cause fatal damage. This adaptation allows them to endure temperatures well below zero degrees Celsius.
Beyond chemical adaptations, individual ants also reduce their metabolic rate. This slowdown decreases energy consumption, enabling them to survive extended periods with limited or no food intake. During autumn, ants accumulate fat reserves, serving as their primary energy source through dormancy.
The Colony’s State During Winter
The ant colony collectively survives winter by relocating to the deepest, most insulated nest sections. Worker ants form tight clusters around the queen and brood (eggs, larvae, pupae), creating a living shield that generates and conserves warmth. This communal clustering maintains a stable temperature for the colony’s core, protecting vulnerable members.
During dormancy, the queen ant typically reduces or ceases egg-laying, conserving the colony’s energy and resources. Larvae enter suspended development, halting growth until spring conditions improve. The colony largely subsists on food reserves gathered and stored during autumn. Some species store seeds in specialized underground granaries, while others rely on stored sugary liquids.
Foraging outside the nest is minimal or absent during winter due to scarce food and low temperatures impeding movement. To further insulate, nest entrances may be sealed, trapping warmth and preventing cold air entry. As cold recedes and temperatures rise in spring, ants gradually emerge from diapause, resuming foraging and reproductive cycles to rebuild and expand the colony.