Inside: It seems everyone has a different recommendation for how long you need to freeze honeycombs to kill wax moths and their eggs. The reason: all freezers are different.
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Killing wax moth eggs requires a hard freeze
This morning a reader pointed out inconsistencies on my website. In one post I wrote, “Freeze honey combs before storing. The USDA recommends 24 hours at 0 degrees F.”
In another post I write, “To kill the moth [eggs], you must monitor both time and temperature. For example, the Mid-Atlantic Apiculture Research and Extension Consortium (MAAREC) publishes the following guidelines to kill both species of wax moth: “20 degrees F for 4.5 hours or 5 degrees F for 2 hours.”
The reader wanted to know, “So which is it?”
The real answer varies with every freezer
The real answer here is “neither” or “both,” depending on how you look at it. These numbers—like so many others in beekeeping—are recommendations or guidelines. They are not rules carved in stone. You’ve certainly heard advertisements that end with the phrase “results may vary,” right? Well, that applies to nearly any beekeeping recommendation, including these.
Most of the time, science doesn’t reveal simplicity. Instead, it exposes complexity. In a simple situation like freezing wax moth eggs, there are far too many variables to give a cookbook answer.
I had a statistics professor in graduate school who loved the word “exogenous.” He would stand in front of the class and hold on to the second syllable as long as he could: ex-ahhhhhhh-gen-ous. His point was that nothing goes uninfluenced by other things. So when your experiment doesn’t work, you say “Ahhhhhhhh! It’s those ex-ahhhhhhh-gen-ous variables!”
So what is an exogenous variable?
Simply stated, an exogenous variable is something that originates from the outside. In this case, factors not measured or considered in egg-freezing experiments are affecting the results.
The examples listed above show the times and temperatures needed to freeze wax moth eggs in two different freezers in two different places by, I imagine, two different researchers.
That the results are different is not at all surprising. Of course they are different. If they were the same, I wouldn’t trust either of them. Exogenous variables, variables not measured in the experiments, affected the results.
Name a variable that might go unmeasured
Now, I don’t know what those variables were. There are probably many, but over breakfast this morning we came up with some possibilities.
- Thermometers: they read differently. Go to a store display of thermometers and take a look.
- People: some may read the thermometer carefully, some may round, or there may be parallax.
- The temperature of the freezer: is it close to your target temperature or much colder?
- The freezing cycle: how warm and how cold does the freezer get during each cycle of operation?
- Defrost cycle: if the defrost cycle runs when the frames are in there, freezing will take longer.
- Temperature of the combs going in: if they are 80 degrees, freezing will take longer than if they are 60 degrees.
- Opening and closing: if the freezer is opened frequently, freezing will take longer.
- How deep in the freezer are the frames: deeper placement means less influence from opening and closing.
- Packing arrangement: If frames are packed tightly, freezing will take longer.
- Condition of the freezer gasket: if it’s old and worn, it may leak, so freezing takes longer.
- Amount of frost in the freezer; frost is an insulator and could change the rate of freezing.
- Front near the gasket could create an air leak and decrease the rate of freezing.
- Size of the load: if you add many frames at once, they will take longer to freeze.
- Thickness of the combs: thicker combs will take longer to freeze.
- Frame wraps: if you wrap the frames heavily, they will take longer to freeze.
- Condition of moth eggs: are they full of water or are they beginning to dehydrate?
- Mass of freezer contents: if lots of frozen goods are in there, the new additions will freeze faster.
I’m sure you can think of others. But as you can see, it would be impossible to calculate all the influences. Instead, we write guidelines that work for most people most of the time. Are they failsafe? Of course not.
How can I make sure the moths are dead?
People often ask how I do it. In truth, I don’t monitor the time, temperature, or anything else. I wrap my frames in plastic film and then place them in the freezer overnight. The next morning, I take them out. Without removing the wrap, I let them thaw at room temperature and then store them in a cool room. Period. I’ve never had a problem.
But my freezer is a big, deep chest freezer with lots of frozen stuff in it. Yours will be different. If you think the freezing was sufficient to damage the wax moths eggs, you are good to go. If not, leave them in longer: f Freeze them until they are hard. Freezing them longer won’t hurt anything at all.
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