Where Do Insects Go In the Winter?

Despite the unseasonably warm days we have had, winter is upon us.  So, what happens to all those bugs that we see in the spring and summer?  There are several different strategies that insects have come up with to survive the cold winter months.

1.  Migration

We all know that birds fly south for the winter.  Did you know there are some insects that do the same?  A great example of this is the Monarch butterfly, which travels all the way to Mexico each winter.  Other insects migrate down into the ground to get below the frost level.



Monarch butterfly; photo courtesy of mexicotoday.org

2.  Communal Living

You've heard the phrase "safety or strength in numbers."  Some insects like ants and honey bees cluster together to make "warmth in numbers."  The bees' wing activity can raise the temperature in the hive above freezing.

3.  Dormancy

Many insects become dormant in a state of hibernation called diapause.  The inactive state of suspension helps synchronize the insect's life cycle with seasonal changes in the environment.  Insects can become dormant at different stages.  For example, praying mantids and tent caterpillars spend the winter as eggs.



Tent caterpillar eggs; photo courtesy of johnston.ces.ncsu.edu

Others spend the winter as larvae.  One example of this is the wooly bear caterpillar, which curls up in thick layers of leaf litter.  The next stage is pupae.  The black swallowtail butterfly spends the winter as a chrysalid, or cocoon.  Still other insects overwinter as adults.  Mourning cloak butterflies, for example, tuck themselves behind loose tree bark or in tree cavities.  Many insects, like ladybugs and boxelder bugs, move in our homes and spend the winter in wall voids and attics.



Black Swallowtail chrysalis; photo courtesy of buglifecycle.com



4.  Cold Hardening

Some insects produce cryoprotectants, or their own "antifreeze."  By producing a glycerol substance, insects can "supercool" themselves which allows their body fluids to drop below freezing points without causing ice damage.  The smaller the amount of water, the better they can supercool without freezing.  Because of this, smaller arthropods like ants or tiny spider mites can cool to colder temperatures than larger insects, like grasshoppers. 

5.  Staying Active

Lastly, a few insects actually stay active during the cold months.  One example of this is springtails, also called snow fleas.



Snow Fleas; photo credit-Jeff Hahn; www1.extension.umn.edu