Introduction to Insect Control in Home Food Storage

Introduction To Insect Control
In Home Food Storage
Insects are a serious threat to everyone's food supply. In 1982 I bought a five gallon jug of wheat from a friend which had been stored for several years. I kept it for about a year then opened it up. Looking down though the 2 inch hole of the jug it looked like the whole thing was moving. It was completely infested with weevil. Rather than even try to do anything with it, I took it out to the dumpster and pitched it.

The big companies have traditionally fumigated using malathion, ethylene dichloride, or ethylene dibromide, which work very well. But there needs to be an effective means of fumigation at home. Well, there is. Back in the late 1980's, a lot of work was done exploring carbon dioxide as a fumigant. The long and short of it was that carbon dioxide worked great on every insect tested, in all their stages of development. Using carbon dioxide as a fumigant is really good news for people packing up their own food for long term storage. It can be easily done with no special equipment using dry ice.

Presently, the food storage companies make use of oxygen absorbers to promote long term storage of foods. Effective bug control using oxygen absorbers requires all the air be removed. And then the authorities are careful to state that removing all the oxygen doesn't necessarily kill bugs, but rather prevents them from thriving should they hatch. Even 0.5% oxygen is enough for many bugs to breath and thrive. So in this way, yes, oxygen absorbers are an effective method of insect control as well - as long as you get rid of all the air.

But oxygen absorbers don't actively kill insects like carbon dioxide does. Another great bit of news about dry ice is it takes as little as 10% carbon dioxide over a relatively short period of a month or so to kill insects. The higher the concentration, the faster it kills them, reducing this time to hours rather than weeks at near 100% concentrations. It's often simpler to get enough carbon dioxide into a container of grain to kill the insects than to get 100% of the oxygen out, and keep it out.

If you are following me here, you may already be asking the question, "Well then, why don't we use carbon dioxide and oxygen absorbers together to get the positive effects of both?" For some reason normal oxygen absorbers don't work very well in a high carbon dioxide environment. The question of wanting to use the two together has some validity because even a good purge using dry ice will leave about 10% air in the container. As air contains 21% oxygen, you'll have a residual oxygen level of about 2%. This 2% oxygen level is inconsequential as far as the already dead bugs are concerned, but some people want to get rid of even this oxygen to promote long term storage of their food. For those of you wanting the very best, I understand Multisorb is making a new 'M' type absorber that will work in a high carbon dioxide atmosphere.

Diatomaceous earth, bay leaves, spearmint gum and a host of other folk remedies have all claimed to have remarkable success over the years in preserving food from insect infestation. These ideas continue right up into the present time. But studies show nothing is as sure for killing insects at home as carbon dioxide, with freezing and oxy absorbers a close second.

Freezing dry goods has been an effective means of killing insects for a long time now. When you freeze your food storage for insect control, Geri Guidetti suggests you freeze it for at least three days. Another study from the Benson Institute suggests freezing it to -23 degrees C at the center of the container for 2-4 hours. There is some question if freezing kills the eggs of all the different types of insects that can infest grain. So if you use this method, it would be a good idea to keep an eye on it so if insects do show up you can take care of them before they run you out of your food supply room.

And lastly, let's talk about the lids. If your containers are well sealed, there's no physical way for insects to get into your bug-free foods. The Benson Institute study in this section reports that plastic lids on top of #10 cans in an insect infested area was not good enough to prevent insects from finding a way into insect free cans of wheat. And bugs can eat through plastic bags.

Summary: I suppose you can tell from reading this page that I think carbon dioxide is truly the way to go in controlling insect infestation. It dims all other methods as far as ease of application and assured results. In my mind only oxygen absorbers and freezing compare as other good choices.

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Al Durtschi, E-mail: mark@waltonfeed.com