Taking care of ants during hibernation, or more accurately, diapause, in winter sounds daunting. I have not seen much information on handling ant colonies in a diapause stage and hence would like to share what I know so that it helps ant keepers.

To care for your ants colony during their diapause (aka hibernation) in the winter, ensure there is enough moisture in the nest and maintain the temperature within 40-50 °F (5-10 °C). If the ants are in a test tube, a standard test tube setup with water will be sufficient; if the ants are in a formicarium, water the nest every few days to keep it moist. At this stage the ants do not require food. 

Not all ants undergo diapause. If you are keeping temperate ants, most likely your ants will undergo diapause in the winter. So what happened to your ants during their diapause and what should you know? Can a diapause be prevented? Continue reading to understand more.

Do my ants need diapause?

Usually ant species of a temperate and mediterranean origins undergo diapause. In the winter, you would notice the ants have become sluggish in their movements, and the queen doesn’t produce as many eggs. This shows a sign of imminent diapause. In contrast, tropical ants do not undergo diapause in winter. 

What happens to the ants during diapause?

Before diapause, the ants will start to build up energy reserves in their body so that they can survive the winter without food. In most temperate species, the workers will stop foraging for food and become inactive in winter. Meanwhile, the queen will rest and stop laying eggs. Larvae, on the other hand, will stop growing. Because their activities are greatly reduced, they can survive with their energy reserves for a few months. 

Meanwhile, the Mediterranean species do not completely stop foraging. They still forage for food, albeit at a very low activity. Hence, you will need to provide them with food.

Can I stop my ants from entering diapause?

Yes, you can stop your ants from entering diapause by preventing the temperature of the nest to drop during winter. However, this is not recommended because diapause is a natural need of ants (that need diapause). By skipping diapause, your ant colony may grow slower, have smaller workers, and have a shorter lifespan in the long run. 

Certain ant species will enter diapause even though you prevent the temperature from dropping. It seems like diapause in those species that are controlled by their biological clock and not affected by temperature. Even if you successfully prevent diapause for 1 or 2 years, certain ant species will randomly enter diapause even if it is not winter yet.

Helping ants colony to enter diapause

To help your colony transit into diapause better, you need to gradually lower the room temperature 2-3 weeks before winter. You can do so by gradually adjusting the heater in your room and eventually turning it off. Then move them to your garage or basement where it is cooler. If you do not have a basement, you will need to put your colony into a wine chiller or mini fridge. When using a chiller or fridge, put them on a higher temperature and gradually adjust the temperature down every day. Do not start with the lowest temperature. Generally you would want to keep them between 40-50 °F (5-10 °C). If you are keeping a Mediterranean species, you can put them at around 60-65 °F (15-18 °C).

Caring of ants colony during diapause

Most ants do not require food during diapause, but they do need moisture. Water your formicarium like you usually do. You will notice that it takes longer for the nest to dry up in the winter compared with summer. Hence, you do not have to water it as frequent. However, if your ants are in a fridge, you need to water more often because the nest will dry up faster. If your ants are still in the test tube, a typical test tube setup with water should last them the whole winter. Check out your ants once every 2 weeks to make sure they are healthy. 

If your ants do not go into diapause completely (such as mediterranean ants), you will need to feed them with 10% syrup. Most likely the feeding of protein will decrease at this moment.

What else should I do when my ants are in diapause?

Rest! This is a once in a year time that your baby does not require much attention. But before you rest, take this opportunity to thoroughly clean your outworld since your ants won’t be using it for the time being. Avoid using detergent with strong fragrance to wash your outworld. 

Getting out of diapause

A complete diapause will last around 3 months. When you are ready to let your ants colony exit diapause, adjust the temperature upward gradually and eventually move them back to their original location. It may take some time for the colony to fully exit diapause, during which they show some “abnormal” behaviors. 

The ants will start to look for food and you should provide them more sugar at this stage. Start introducing protein when you see them fully active. Premature ending of a diapause is possible, but it may cause the colony to remain sluggish for a long time and might have some bad effect in the long run.

Some of the ants in your colony will not make it through the winter but it is perfectly normal. 

What should I do with my tropical ants in winter?

Provide your ants with additional heat using heat mats or heat cables (affiliate link here) during the winter. Food should be provided as usual and humidity should be maintained. Tropical ants typically grow faster than temperate ants. If your colony has grown relatively bigger, consider moving them into a larger nest. Some formicarium designs allow you to expand your nest with minimum disruption.

Other information

Winter Ants

The winter ants (Prenolepis imparis) are active in the winters but not summer. These ants are active at 35-55 °F (2-13 °C) and they continue to forage even at temperatures as low as 6 °F (-14.4 °C). If you are keeping this species, you would need to constantly put them in an air-conditioned room or even in a chiller.

Diapause in summer

Ants originated from warm arid regions may enter diapause in the summer when the weather gets too hot. To stay safe, they will spend more time in their nest instead of foraging for food. Similar to ants that enter diapause in winter, these ants exhibit lower metabolism, slowed development of larvae and eggs laying.

Most of the time the ants will not enter diapause if you keep the conditions favorable for them in the summer. However, some species do enter diapause even when the conditions are favorable.