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Monday morning myth: freezing won’t kill wax moths

Contrary to popular hearsay, freezing will kill all life stages of both the greater wax moth (Galleria mellonella) and the lesser wax moth (Achroia grisella).

To kill the moths, you must monitor both time and temperature. For example, the Mid-Altantic 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.

Similarly, the Department of Primary Industries in Victoria, Australia advises

-6.7 degrees C for 4.5 hours or

-12.2 degrees C [10 degrees F] for 3 hours or

-15 degrees C for 2 hours

These numbers convert exactly. Nevertheless, beekeepers come up with all kinds of wild stories about freezing them for weeks on end, only to have the caterpillars start crawling around when the frames thaw. Don’t believe it.

Here are some points to consider if you freeze your frames for wax moth control:

  • Check your freezer temperature with a reliable thermometer—don’t depend on the dial.
  • Measure times from the point when the frames, combs, wax, or super reaches the desired temperature. Don’t start timing from the moment you put them in the freezer.
  • Remember: if you return thawed frames to a super that was not frozen, re-infection can occur immediately.
  • The same is true if you return frames to an area that contains adult wax moths, such as a storage building or honey house.
  • If you wrap frames tightly in plastic wrap before freezing—and leave them wrapped afterwards—you can protect them from re-infestation. Wrapping also keeps condensation from forming on the combs and frames while they return to ambient temperature.

Freezing times don’t have to be exact as long as you meet the minimums. For example, my freezer is 9 degrees F. I just wrap my frames in plastic and freeze overnight . . . or over 30 nights. There’s no need to create an ordeal.

One reason the myth persists is that some beekeepers have reported that wax moths survived the winter in their hives in spite of the fact it was less than 20 degrees for weeks on end. This is most likely true because it is not 20 degrees inside a healthy beehive. The cluster keeps the wax moths warm and cozy all winter long. But as long as the colony remains healthy and strong, it will destroy most of the moths as it expands in spring.

So just remember, wax moths are not an inexorable pest destined to take over the world—they are both predictable and manageable. When the day comes that they can drop me in the freezer, then I’ll start to worry.

Rusty
HoneyBeeSuite.com

Comments

ET Ash
Reply

Freezing also kills the small hive beetle (larvae and eggs). Actually in regards to both the small hive beetle and wax moth it is really the egg stage that you need to worry about the most.

April
Reply

First time on this site. Does anyone have any good info on fighting the hive beetle? I lost my Russian hive this past summer, so bought a bottom board with large holes and oil pan for my Carniolan hive. So far my Carniolans are ok. Live in Missouri. Thanks.

suz
Reply

I hear that you can keep drawn foundation in 24 hours light to keep away wax moths….?

Rusty
Reply

You can store drawn foundation in a place with lots of light and good ventilation. This will keep infestations down if the combs are not already badly infested. Or you can freeze the combs for 24 hours and then store them in a moth-free place. Keeping comb in light for just 24 hours won’t do much for moth control.

Lin Beek
Reply

I don’t know what to believe! We had wax moths in a bunch of stored equipment and comb. Looked on line to see what would kill these little critters. Wrapped everything in plastic garbage bags, and arranged to take the whole works down to a commercial freezer which registered 18 degrees. Left the equipment for 22 hours. You would think that should be plenty of time for everything to get good and cold. Took it back home, and checked the bags ….. wax worm alive and well !!!! Now I just have it all piled outside in the garden and waiting for some extended cold weather before I do anything else with it.
Will the worms, eggs etc be dead by the time spring arrives? Really? We get sub zero weather at times and I am hoping, but don’t know “weather” it will take hours, days, or weeks of cold.

Rusty
Reply

Lin,

With everything wrapped together in a plastic bag, it will obviously take more than 24 hours to get everything solidly frozen.

Maria
Reply

After several rainy weekends that prevented us from checking our hives, we went into them this weekend and discovered they were basically gone. There were a hundred or so bees, several open queen cells, and evidence of wax moth, though far from an infestation. There were a few hive beetles and lots of stored nectar and some honey. We shook what was left of the bees down into one box and continued feeding them a 2:1 syrup. We’ve pulled the frames with evidence of webbing and will freeze it. I’m not hopeful for the few bees left, but didn’t really know what else to do with them. There was so little brood left and what was there contained half emerged, dead bees. I guess once the rest of the bees die off, we’ll freeze the rest of the frames. Can we reuse them in the spring – will the bees clean them up or do we need to re-wax them? Is there anything we should do with the hive boxes? Should we be worried about the hive next to it? There was no evidence of moths in there. Also, if we freeze the frames with honey and nectar in them, will it be ok to feed back to the bees? Lots of question, I know. We’re very sad to have lost our first hive. Thanks for any further guidance you can offer.

Rusty
Reply

Maria,

There’s an old saying that beekeeping doesn’t take much time, but the necessary steps must be done on time. By going in several weeks ago you may have saved a lot more bees. Rain and cold would not have killed nearly as many as waiting.

But about your questions…Once you wrap and freeze the frames, you can store them at room temperature until spring and then place them back in the hive. The bees will clean them up. You don’t need to do anything with the boxes. If you have frames in there that once contained brood, you want to protect those from wax moths. If you live where it freezes, you can just store the frames (and boxes) in a cold place that freezes, like a shed. You don’t need to worry about the adjacent hive as a healthy hive can take care of the moths and usually the beetles as well. Previously frozen honey and nectar is fine for bees. You can just give the frames back to them.

Maria
Reply

Thanks so much. Lesson learned.

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