Thawing Frozen Bugs; The Grand Experiment

A few weeks ago, I wrote a post about seeing insects frozen in ice, and speculated about how they’d gotten there and whether or not they might still be alive.  Several of you encouraged me to chip them out of the ice and thaw them out, apparently under the impression that I walk around with an ice axe in my camera bag.  Nevertheless, it was a fair point.  Why speculate aimlessly about something that’s relatively easy to test – especially since it wasn’t the first time I had speculated on the same topic?  (See this post from 2014 and this one from 2011.)  For my 2014 post, I actually did pull a beetle out of the ice and watched it thaw.  It was dead.

Yesterday afternoon, I went out to our family prairie with two of our boys.  Daniel needed to do some video work for a school project, and Calvin wanted to continue working on a project he’d started over the weekend, which seems to involve propping sticks against a tree.  Anyway, two boys wanted to go to the prairie – what am I going to do, say no?  We went.

The boys had a great time playing on the ice while I was looking at dead bugs.  I should maybe reevaluate my life choices.

It was about 60 degrees when we got to the prairie, and while the wetland was still frozen enough to walk on, the top of the ice was melting.  Scattered about the wetland and a nearby livestock watering tank were numerous insects that had been frozen yesterday but today were sitting in shallow puddles of water on top of the ice.  Ah ha!  No ice axe required today!  I grabbed a ziplock bag from my pack (an item even more essential to a naturalist than an ice axe) and starting scooping up cold insects and enough water to keep them in.

A cell phone photo of a couple insects on the frozen surface of a livestock watering tank.

When we got home, I dumped the bag of pond water and insects into a shallow bowl.  The following is a series of observations as I conducted this important scientific research project.

A bowl of bugs on my kitchen counter.

February 26, 2018

6:05 pm – Dumped 18 insects into a bowl, having collected them from thawing water on top of the ice at our prairie.  (No ice axe required, thank you.)  Initial observation: the insects appear to be motionless.  Some are floating, others are submerged.  Water is still very cold.

6:31 pm – Added a little warm water to the bowl.  Some of the insects moved as I dumped the water in, but seemed to settle back into stillness as the water calmed.  Brief movement considered inconclusive as to the status of insects as living or dead.  More data needed.

7:48 pm – Water is about room temperature now.  Wondering if the floating are the same that were floating earlier?  Probably.  A couple stray legs seem to be lying around on the bottom of the bowl.  If those insects are soon to be alive and kicking, it appears they’ll have fewer legs to kick than they had last fall.

A stray leg.

8:33 pm – Of the 18 insects I collected and put in the bowl, 18 still appear to be motionless.  Fighting boredom (me, not the insects).  Must remain vigilant in order to complete this project for my readers.

9:07 pm – Nothing to report.

10:15 pm – I’m pretty sure several of these insects are actually flies, and not aquatic insects at all.  Wondering if I should remove those from the dataset so as not to bias the overall survival rate.

Waiter, there’s a fly in my soup.  Oh? What’s it doing?  Nothing.  (Not a funny joke at all.)

10:56 pm – So tired.  Can’t keep my eyes open much longer.  Have decided to call it a night and hope not to lose any insects that reanimate during the night and fly off.  Will cover the bowl to be sure. One of the water boatmen has a certain look in its eye – just waiting for me to go to sleep so it can make its escape?  Better seal the bowl tightly…

February 27, 2018

6:15 am – Woke up and immediately remembered the insects.  Hoped none had eaten each other or escaped.  Scurried out to the kitchen and did a quick count.  All 18 insects accounted for.  None seem to be moving.  Sleeping after a busy night of swimming?  Swished the water around a little, and got some movement, but didn’t seem to be the result of any self-propelling motion by the insects.  Hopes diminishing.

7:10 am – Have decided that maybe the water temperature needs to be higher in order to break diapause.  Added hot water to the bowl.  Awaiting developments.

7:15 am – Trying to fix breakfast and school lunches.  Need counter space.  Re-evaluating this entire project.

7:23 am – Adapted Monty Python sketch running through my head…  “These bugs are no more!  They’ve ceased to be!  They’ve expired and gone to meet their maker!  They’re stiffs!  Bereft of life, they rest in peace!…These are EX-BUGS!”

Figure 1. Number of dead bugs compared to number of live bugs.  Error bars represent 95% confidence intervals.

7:24 am – Ok, I’m calling it.  Experiment over.  These insects are dead, folks.  Of the 18 frozen insects removed from the surface of the ice, 18 died.  This evidence strongly supports the suggestion that insects found embedded near the surface of frozen wetlands are, in fact, dead.  This follows the findings of Helzer (2014) who similarly found a frozen beetle to be dead upon thawing.

Pining for the fjords?  Nope.

Ok?

Ok.  I’m going to clean out that ziplock bag now and get it back in my camera bag.  I don’t want to be left without it when the next scientific opportunity presents itself.

Frozen Bugs (and Beetles)

My family and I spent some time exploring the frozen pond/wetland at our prairie during the holiday break.  We even got a couple days of great ice skating weather.

My three kids had a great time ice skating on the pond over the holidays.
My kids had a great time ice skating on the pond over the holidays.

While we were on the ice, we found some great patterns (see earlier post), but we also found quite a few frozen insects.  In particular, there seemed to be two species of insects – one bug and one beetle – encased in ice.  The bug was a species of Corixidae, or water boatman.  Its name comes from the fact that two of its legs are extra long and sport hairs that make the legs look and function like the oars on a boat.  Water boatmen suck the juices from algae and plants through their long straw-like beak and are common inhabitants of just about any freshwater body around here.  They are also frequently seen in the ice when those water bodies freeze up in the winter.  Apparently, water boatmen can survive freezing and just start swimming again when the ice thaws.  A pretty neat trick for an aquatic bug that lives in a temperate climate.

A frozen water boatman
A frozen water boatman

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Another one
Another one

We had a two day period over the holidays during which the temperature briefly climbed up to about 60 degrees (Fahrenheit).  The warmth didn’t last long enough to spell an end to our ice skating, but did melt some of ice along the edges of the pond.  Apparently, the warm temperatures also encouraged a number of individuals of one particular beetle species to go exploring.  Unfortunately, it appears quite a few of those beetles wandered out onto the ice and didn’t make it back.  We didn’t see any of them on the ice before the warm spell, but found lots of them afterward.

Here's one of the beetles that froze after (apparently) getting caught out on the ice after a warm day.  I'm hoping one of my entomologically-inclined friends can help me out with identification and/or natural history info?
Here’s one of the beetles that froze after (apparently) getting caught out on the ice after a warm day. I’m hoping one of my entomologically-inclined friends can help me out with identification and/or natural history info?

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This beetle apparently got flipped over before freezing.
This beetle apparently got flipped over before freezing.

I was curious to know whether those frozen beetles could do the same thaw-out-and-re-energize trick as the water boatmen, so I broke off a chunk of ice containing a frozen beetle and brought it home to thaw it.  The beetle has been thawed out for more than a week now, and hasn’t moved, so I’m pretty sure it’s dead…  The next question is: where were those beetles staying during the very cold weather earlier this winter, and how did they prevent themselves from freezing to death then?

Always more questions…

For more information on how water boatmen and other creatures weather the winter, see this earlier post from 2011.