The Inside Job

Reader Alan responded to the below post on sifting with a story about a recent kitchen moth invasion. It reminded me of something similar that happened here in the pastry household about a year ago. Most of us have had the experience. You’re doing dishes one evening and you notice a couple of little moths with stripey wings flitting about. Who let these darn things in here?

“Honey,” you call to your spouse in the next room, “we’ve got to make sure we’re keeping the screen doors closed. Moths are getting in.” But of course no one is letting the moths in. You and I are bringing them in — in our packaged flours and grains.

Insect eggs and other, ehem…impurities…are in all flours, however they’re more likely to be alive in freshly milled and/or organic flours because those products aren’t treated with fumigants (otherwise they wouldn’t be organic). Left sitting around long enough nearly all of those products, and even many treated flours and meals, will eventually hatch moths, usually Indian meal moths but also Mediterranean flour moths. Both are extremely common US pantry pests, and each have a life cycle of about six weeks. So if you don’t want them to hatch, you need to hurry up and eat them. You need the protein anyway.

Something I find interesting about pantry moths is that they don’t occur on or near wheat or corn crops in the field. Rather they’re specifically adapted to human activity (milling and the like). And are they ever destructive. Globally, it’s estimated that humans lose something on the order of $10 billion worth of milled grain to moths every year.

But I know what you’re thinking: if conventional flours have fewer live moth eggs in them than the more natural alternatives, why don’t conventional flour makers talk about that? The answer is: are you kidding? It’d be like a politician standing up and saying “My opponent has solicited sex from prostitutes over a dozen times, while I myself have only done it twice!” When you’re talking moth eggs, the winning answer is always to keep your trap shut.

This is why conventional flour manufacturers never respond when natural food advocates ask them why they won’t stop using bleaches and fumigants on their flours. “Because if we don’t, the insect eggs in it will hatch out.” Talk about a poor PR message. It’s also why organic flour makers and smaller specialty millers can crow endlessly about never using bleaches and fumigants without having to worry about a response from the likes of General Mills. “Sure their products may look and taste more natural, but in the end their moth eggs will end up hatching a whole lot faster than ours!” It tends to depress sales.

So if you wonder why organizations like the military or international relief organizations always distribute processed white flour when there’s a famine or disaster somewhere in the world, this is the reason: because processed white flour is the most sanitary, and it can be kept a lot longer. 

But a word to the wise baker: of you’re keeping a lot of flour around it’s best to keep it in the freezer. This is especially true of organic flours, but it’s a good rule of thumb just generally. Freezing not only kills off (or stunts the development of) pests, it prevents any oils in the flours from spoiling. Plus it frees up pantry space. If you don’t have that kind of freezer space available then the best course of action is to use mass-market bleached flour and keep it in a sealed container. That way, if any critters are born on-premises, they’ll have nowhere to run.

6 thoughts on “The Inside Job”

  1. We once left our house for 6 months. When we got back home our pantry was rife with them. I think it took another 6 months to eliminate all of them without using anything toxic.

    Since then I use a vacuum sealer and reseal everything I’ve opened. The vacuum isn’t important it’s keeping what’s inside in and what’s outside out. If something hatches I can throw that item away lickety split without concern that any beastie’s been able to invade anything else. I have to put things with paper wrappers into plastic bags or storage bins with silicone gaskets but most things have an inner seal that works fine in the vacuum sealer. …even multiple times as you work your way to the bottom.

    I know the freezer is the best storage medium. Especially for whole grains with volatile oils. But I just don’t have that kind of space in mine.

    1. That’s a great solution nonetheless, Rainey. Others may benefit from your innovative thinking!

      Thanks for the comment!

      – Joe

  2. Thanks for the insight. That was precisely how it unfolded for us: “How did that moth get in here?” and, later, “Why are there two more moths in here?” And our first instinct was to protect our clothes, even though the moths were in the kitchen, nowhere near our clothes.

    Ultimately, I think we did conclude that it was an inside job, with the pattern of destruction suggesting that ground zero was a long-forgotten bag of peanuts — unusual in this house, since peanuts don’t usually last more than a few days here — purchased in bulk from an organic shop. Not sure what species our moths were, and I was a bit surprised they went for the peanuts, but the state I found those peanuts in was nightmare fuel.

    Our infestation spread to containers that we knew were not airtight, but that we thought sealed tightly enough to keep pests out. They seem to be able to get through the tiniest opening at some stage of their lifecycle. Nothing that seals with a rubber gasket was affected. We’ve since moved everything into canning jars of various sizes; as Rainey points out above, sealing them in seems like a good way to prevent spread in the event of a future invasion — er, inside job.

    1. Especially for people with more than a casual interest in food, this sort of thing is more or less inevitable. Glad you got the problem under control. While I don’t seal things to the extent that Rainey does (it’s a darn good method by the sound of it), I generally make sure flours and grains are kept airtight. Still the odd critter tends to show up every now and again as I tend to get careless.

      Thanks for the comments and the inspiration!


      – Joe

  3. I generally put everything in the freezer, but just for 2-3 days or so and then it goes into the cabinet. I don’t have the freezer space to always keep stuff in there. If the critters are dead after a few days, they ain’t coming back to life. I have found these other bugs, tiny crawling things, on my food shelves. I have no idea what they are. I emptied the shelves and sprayed with a water/white vinegar solution, which did the trick. So much for uninvited guests.

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