How to Hibernate Your Ants (UK Overwintering)

Most native British ants spend winter in a state of rest called diapause. In the wild they slow right down as the days shorten and temperatures fall, and captive colonies of temperate species need the same. It feels counterintuitive — deliberately chilling your ants — but for a UK-native species, a proper winter rest is part of keeping the queen healthy and long-lived.

Why it matters

• Queen longevity — repeatedly skipping hibernation can shorten a queen’s lifespan.
• A natural brood cycle — the winter pause resets the colony for a strong spring.
• It’s what they’re built for — Lasius, Myrmica, and Formica evolved for a temperate year.

Tropical species are the exception — they don’t hibernate. Everything below applies to UK-native and naturalised temperate species.

When to start

Hibernation is cued by shortening days and falling temperatures, so follow the season: begin easing colonies down around October–November and bring them back around February–March. You don’t need to force darkness; a naturally cooling, unheated space does most of the work.

What temperature

Aim for 5–15°C, and never let them freeze. Suitable spots include:

Setting	Notes
Unheated room / garage / shed	Simplest option; watch it doesn’t drop below freezing
Outbuilding	Fine if insulated from hard frost
Wine cooler	Excellent, stable, adjustable temperature
Fridge	Works with care — stable temp, not too cold, guard against drying

How to do it

1. Taper feeding as the colony slows — they’ll eat far less, and you don’t want food rotting in a cold nest.
2. Keep water available — the test tube reservoir or hydration should not dry out.
3. Cool them gradually over a week or two rather than moving them straight into the cold.
4. Leave the colony dark and undisturbed; expect the ants to cluster and go still. This is normal.
5. In late winter, warm them gradually back to room temperature and resume feeding.

Small colonies overwinter perfectly well in their test tube; larger ones stay in their nest. Warmth and heating equipment come back out only when hibernation ends — see the heating and humidity guide.

Common mistakes

• Too warm — a colony kept at room temperature never truly rests.
• Too cold — freezing can kill the colony outright.
• Drying out — cold air is dry; a reservoir that empties is a real risk.
• Disturbing them — resist the urge to check constantly, as with other founding-stage mistakes.

Not sure whether your species needs it? Each species care card notes its hibernation requirement.