Short answer: most native Canadian ants need 2–4 months of hibernation at about 5–10 °C (up to 12 °C also works). Typical lengths are 4 months for Lasius and Camponotus, 3–4 months for Formica and Crematogaster, and 2–3 months for Myrmica. Aphaenogaster, tropical and greenhouse species, Messor and western harvester ants don't need hibernation.
Hibernation length by genus
- Camponotus (carpenter ants): about 4 months. Chestnut carpenter ants are active year-round.
- Lasius: about 4 months.
- Crematogaster (acrobat ants): 3–4 months.
- Formica (field ants): 3–4 months.
- Brachymyrmex, Tapinoma, Temnothorax, Solenopsis: about 3 months.
- Myrmica: 2–3 months.
- Tetramorium (pavement ants): can be kept without hibernation, but do best with about 3 months.
- No hibernation needed: Aphaenogaster (winnow ants), tropical and greenhouse species, Messor, and our western harvester ants (Pogonomyrmex occidentalis).
Many species mainly need hibernation in their first year. Without it, they produce no workers, or fewer and weaker ones. After that it's optional for some Formica, Myrmica and Camponotus, but native species generally do better with it: skipping it can shorten the queen's life and reduce laying.
Is my colony getting ready to hibernate?
- Less activity and foraging.
- Swollen, food-filled gasters (abdomens).
- The queen slows or stops laying, and larvae stop growing. Camponotus larvae can shrivel slightly and turn yellow.
- Formica stop producing brood altogether.
Some colonies show no signs at all. We often start hibernation as early as October.
How to hibernate your ants
- Feed heavily first. The colony lives off its food stores over winter. As fall approaches, the ants may start eating less on their own, which is normal.
- Cool them gradually over 1–2 weeks rather than all at once.
- Pick a spot at about 5–10 °C: a mini fridge, wine cooler, or cool garage. About 5 °C is a good catch-all. Make sure test tubes can't freeze.
- Check the water about once a month. A cold nest dries out much more slowly, so water about 2–3 times less often than usual.
- Don't feed most species while they're hibernating, though offering a little sugar is safe. Ponera and Stigmatomma are exceptions and must eat.
- Warm them up gradually over a couple of weeks, then resume normal feeding. They can take a while to become active again.
Frequently asked questions
Can I hibernate ants in my kitchen fridge?
Yes, as long as it stays around 5–10 °C and the test tubes can't freeze. A separate mini fridge or wine cooler is easier, because it isn't opened as often.
What happens if I don't hibernate my ants?
Species that need it may produce fewer or weaker workers, and the queen may live a shorter life. Species that don't need it, like Aphaenogaster and tropical ants, are fine at room temperature all year.
Can I buy ants in winter?
Yes. We ship with a heat pack in winter, and many native colonies ship already hibernating.
More detail: Guide to Hibernation.