What Happens to Ants in Winter?

dog antsI always wondered what exactly happens to ants in the Rocky Mountains during winter?  I see them all over in the summer, then I don’t see them during the cold, snowy winter, yet they are back the next spring and summer.  It makes me wonder what they are doing all winter.

First you need to remember that there are thousands of different kinds of ants in the world.  Those ants have different ways of surviving winter and some of them live in the tropics where winter does not actually get that cold nor is there snow.  But, generally in areas that get snow and stay below freezing ants are hiding somewhere and enter a sleep like state called ‘diapause’.


In diapause, bugs replace the water in their bodies with glycerol, something that does not freeze as easily. This is like putting an anti-freeze in their body, which is the same thing we put in our car engines to keep them from freezing.  If their bodies were still full of water then the water would freeze, which would likely kill the bug.

During diapause there is no development, growth, or movement happening. In other words, it is as if bugs simply take a break until the conditions outside are more favorable.  Diapause is a period of dormancy for bugs, similar to how trees go dormant during winter.

In the Rocky Mountains during winter the temperature gets below freezing and there can be a lot of snow piled up on the ground.  The cold temperatures and snow cause the ants to enter into diapause, but where they choose to do so depends on the kinds of ant they are.


Some ants live in a colony in the ground.  On the surface of the ground is a giant ant mound.  These ants go deep enough down in their nest under ground so that they are below the frost line, which means it does not freeze.

In wood

Some ants hide in wood or bark of trees.  For example, carpenter ants live in nests in wood.  During the winter they stay in their nests in the wood.  They can’t get below the freezing line, and the wood may freeze.  In order to survive this they go into a state of diapause.