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!".

Brrrrr- Baby It's Cold Outside!

Have you been outside today? I would think that somehow I got transported back to Ohio if I weren't currently sitting in my office in Austin listening to Christmas carols. Holy crikey- it's COLD! There was a reason that I moved to Texas....to avoid the COLD!

The good things about the cold turn in the weather:
1. hubby is excited that it might snow (being a Texan, things like snow excite him while I've had my fill of snow while tramping around Ohio State- walking to class in snow/slush & freezing temperatures is not a good time)
2. the boy might get to see snow for the first time- great photo op, right?
3. mulled cider and hot chocolate- mmmmm
4. deer chili- double mmmmm
5. it helps my Christmas spirit

Okay, so onto the buggy part of this post. I often get questions- mostly from children- about where bugs go during the winter. Adaptations that insects have to survive the winter:

1. Migration
Insects move to a location where temperatures are not as cold. The most well known example of migrating insects is probably the Monarch butterfly.

2. Freeze tolerance
Some insects are able to survive having some of their body tissues frozen. When temperatures warm up, the insect "thaws out" and goes about it's business.

3. Communal living
Many insects will cluster together and use collective heat to survive freezing temperatures. Ladybugs are a good example. The video below is a clip I took on a recent trip to Ohio. The ladybugs begin aggregating each fall and usually find their way into my parent's house. The video shows them gathering on my grandparent's motorhome.



4. Insect antifreeze
(read on...this is going to make great dinner conversation for you tonight!)
Some insects produce glycerol, a compound similar to anti-freeze, in the fall to prepare for overwintering. These compounds allow body tissues to supercool and remain above their freezing point.

So now that you know how the bugs are going to survive tonight, what do you have in mind to keep warm?

Migrating Dragonflies

Have you been noticing dragonflies lately?

This information is provide courtesy of Forrest Mitchell, Professor of Entomology with Texas AgriLife Extension. Forrest has a site & a book on dragonflies.

"Although there are a lot of different species of dragonflies and damselflies in Texas (currently 231 according to Odonata Central, see below) not many of them will pick up and migrate as you have already noticed by the stable numbers in your backyard. In the appendix of A Dazzle of Dragonflies are 26 (I think) species listed that may be migratory, but there are two species mainly responsible for these current mass movements that I am seeing: the wandering glider (Pantala flavescens) and the spot-winged glider (Pantala hymenaea). My best scans can be found here:
http://www.dragonflies.org/l_cat2.htm
about halfway down the page.
You can see more pictures and scans of them here:
http://stephenville.tamu.edu/~fmitchel/dragonfly/Libellulidae/panta.htm
You can find write-ups on both species here, as well as the 'Species of Texas' checklist:
http://www.odonatacentral.org/index.php/ChecklistAction.showChecklist/location_id/64
Odonata Central and John Abbott are where I go with my questions.

The rainpool gliders are adapted to breeding in temporary water, hence their name. If they have enough to eat, the wandering glider can go from egg to adult in less than 30 days during the summer, so the water only needs to last that long. A dozen or so spot-winged gliders developed in a shallow fountain one summer on my deck. I don't know how long it took since I didn't notice them until they were over half-grown. They ate insects that fell into the bowl, midge larvae and any other dragonflies that were deposited after they were. Rainpool gliders will lay eggs in nearly anything that can hold water including buckets, saucers, flower pots, water troughs (a favorite), puddles, ditches and swimming pools. They will attempt to lay eggs on shiny car hoods, wet asphalt and wet concrete. I have noticed that the wandering gliders will lay eggs in water that is in open sunlight, while the spot-winged glider will lay in the shaded pools and water.

A lot of the South is in a drought, but these dragonflies are able to stay aloft for long periods of time and do not need to originate from a close-by source. In fact, the wandering glider is found throughout the world except where it is too cold year-round. Work in the last decade on the eastern seaboard of the US shows that moving dragonflies are swept together and collected by weather fronts. These concentrations may then be deposited elsewhere and a long way off. We have had several cool fronts along with heavy localized rain to make rainpools and either or both may be what accounts for the presence of so many dragonflies in our region. I am noticing them mostly over stretches of roads and parking lots or wide open fields where the hunting is good. They may be in other places as well, but harder to see.

Just as fronts can bring dragonflies, fronts can also take them away. Enjoy watching them while you have a chance. In case they disappear, I've enclosed a scan of another migratory species, the common green darner to look at. They tend to move in September-October in our part of the world and are often seen by people doing monarch counts during the butterfly migration. I had another letter asking me about this species, so I pulled it out and made it a workable size. Feel free to post it on the DMN website for your readers and/or print it in your column. Credit James Lasswell, my coauthor on the book, with its construction. If printed on glossy paper with a good inkjet or laser printer, it is suitable for framing. Or so I think, but then I am biased."