Cornmeal magic – the myth that will not die

Way back in 2010 (and then again in 2012) I wrote about a bizarre belief that cornmeal could be used to treat fungal diseases, from lawn spot to athlete’s foot. Rather than rehash what’s already been written, I’ll invite readers to read those posts for background. And of course look at the comments, which are…interesting.The weird thing is that this post from 2010 is the single most popular post on the blog. (Our stats are only for the last two years since we migrated the web site – who knows how many there were before May 2017?)

Blog stats over two years

The consistent popularity for the topic spurred me to publish a university fact sheet on the use of cornmeal and corn gluten meal in home landscapes and gardens. This fact sheet reviews the pertinent literature, and makes recommendations that are pretty much the same as those I made almost 10 years ago. Nothing has changed in the research world to support cornmeal as a fungicide.

But wait, there IS something that’s happened since 2010! Now cornmeal is being touted as an insecticide! In fact, if you go to Google and search for “cornmeal” and “insecticide” you’ll find thousands of hits.  As you might expect, there’s no research to support this notion: researchers in Maine, for instance, found no effect of cornmeal on fire ants. However, it is used as a bait to deliver actual insecticidal chemicals.

Way back in 1937.

But facts don’t get in the way of home remedies, such as Lifehacker’s eyebrow-raising advice.


By refining the search to only include university websites (use “” to do this), and swapping out “ants” for “insecticide,” you’ll find at least one Master Gardener group happily (and illegally) recommending cornmeal as an ant killer. The popular mode of action is either (1) they can’t digest cornmeal and starve or (2) the cornmeal absorbs water in their gut and they explode.


This reminds me of yet another food product – molasses – recommended for killing ants. Since you’re already here, you might as well check out Molasses Malarkey parts 1, 2, and 3 too.

Might I recommend everyone use their cornmeal and molasses to make bread or cookies or pancakes? There are some delicious recipes on the internet.


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Linda Chalker-Scott

Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and a Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award. "The Garden Professors" Facebook page - "The Garden Professors" Facebook group - Books:

10 thoughts on “Cornmeal magic – the myth that will not die”

  1. Thanks once again, for your patient explanation that corn meal (and corn gluten meal) has no fungicidal or insecticidal properties.

  2. Grits are what I see as an ant killer. It’s the “ants eat grits, the grits absorb water, and the ant explodes” version. I have been thrown out of 2 local gardening groups this year for posting the life cycle of ants to show how silly that is. You wouldn’t think that would be controversial. You would be wrong.

    I was going with the life cycle of ants rather than other evidence like linking any kind of scientific study to avoid the knee jerk hostility that seems to elicit. Obviously, that didn’t work, either, but I did try.

  3. Since cornmeal comes from field corn, and it is sprayed with pesticides, could it be a false assumption that cornmeal “ doesn’t have insecticidal properties”?

  4. Actually Shannon is on to something. Isn’t something like 90% of our corn a GMO corn. Such as BT corn, which has the insecticidal Bacillus thuringiensis protein in the plant tissue now? So yes it would likely have insecticide in it unless you were buying a non GMO brand? It may not explode them but maybe it could kill ants now.

    1. The proteins made by the Bt genes certainly can end up in the corn kernels. Where it ends up during processing into corn meal (mainly carbohydrates), corn gluten meal (much of the protein), and other byproducts…I couldn’t tell you. But in any case it won’t kill ants – Bt proteins target a relatively small group of insects that does not include ants.

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