It's freezing outside. Why are all the insects not dead?

So as I sit in my cozy office (with my sweater, scarf, fingerless gloves, and heater) I consider the poor insects that are having to deal with the drastic flip-flopping of the weather the past few weeks.  We've seen temperatures in the 20's and temperatures in the 80's, so I'm sure that they are a bit confused.  I was asked last week when it was warm how the mosquitoes came back so quickly if they died when it was freezing.  Well.......

Insects have certain adaptations that allow them to survive when temperatures get cold.  If you really think about it, they still have bugs in Minnesota when it warms up and they have to deal with much colder and longer winters than we do here in Texas (just ask my neighbors who are transplants from Minnesota).

Just like the snowbirds that drive their RVs to Texas or Florida to spend the winter, there are certain groups of insects that migrate to new areas to spend the winter where temperatures are not as cold.  A great example of this is the Monarch butterfly.

Another example that can be put into "human relation" terms would be insects that use cryoprotectants (anti-freeze compounds).  The most commonly used compound that insects use for this purpose is ethylene glycol, which is the same compound that is in antifreeze that humans put into our vehicles.  Ethylene glycol allows the insect's body tissues to supercool and remain above their freezing point.

Freeze tolerance is another modification that some insects use to survive freezing. With this method, freezing causes water to be forced out of living cells and causes the fluid around them to freeze.  These insects also need to empty their digestive tract as food can hold water which could freeze and cause problems.  Freeze tolerance is easier for smaller insects due to the fact that they have less fluid in their body because of their small size.

Some insects may gather together to create collective heat.  Honey bees do this inside the hive during the winter to keep warm.

Other insects seek areas of shelter in the immediate area where it is not so cold.  A good example of this is the ladybugs from my previous blog post.   These insects move into homes through cracks and crevices or other areas that are not well sealed when it gets cold.  This can lead them indoors to become nuisance pests.

I haven't covered all the methods that are used, so don't expect all the bugs to die just because it's freezing outside.  Like the Terminator...."they'll be back!".