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Garden Update ~ How to Kill Cucumber Beetles, Organically

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The bugs are horrendous this year. Several people have told me that the bugs would be bad this year, but when I ask why, I get no good answer. The best answer I have heard: it just cycles and this is the year for bad bugs.

how to kill cucumber beetles organicallyFor three years in a row now, I have lost my cucumber crop to the blasted cucumber beetles. One of my favorite foods to preserve from the garden is my Grandmother’s Secret Dill Pickles, and so the loss of my cucumber crop really breaks my heart. Last year I was able to can a few quarts because some good friends gave me some of their excess cucumbers, but I have not had a good pickle canning session for many years now.

Here's what a cucumber beetle looks like - keep and eye out for these pests! They're cute but they're SO destructive!

Do you see that nasty little yellow and black striped bug on my cucumber plant? They may look all cute and harmless BUT let me tell you, they are real, real pests. They are very destructive.

Sick of cucumber beetle destruction? Here are some organic methods to kill those annoying pests and save your plants.Besides being able to eat cucurbit leaves in a matter of days, they also cause bacterial wilt which kills the plants. I can live in harmony with many bugs, but not these guys. Killing my cucumbers means war, and I am tired of losing that war!! I’ve tried a few things to kill cucumber beetles over the last few years, but nothing’s been successful. Until this year. This year, I caught them early. And I struck hard and I struck fast.

How to Kill Cucumber Beetles, Organically

This year, I turned to Diatomaceous Earth. Last year, when I found the dang beetles, I read that food grade Diatomaceous Earth can be used as an organic insecticide, so I ordered a 50 pound bag from Azure Standard. According to the National Pesticide Information Center, Diatomaceous Earth is a type of silica made from the fossilized remains of diatoms. It’s a fine,white powder and it’s edible. Under a microscope, it supposedly looks like shards of glass and it is deadly for any bugs with an exoskeleton, like cucumber beeltes, and fleas, and all sorts of nasty parasites. You can read more here at this useful article by Paul Wheaton.

I have read that you should be careful not to inhale DE, but last year when my husband suffered from intestinal parasites, I broke out the DE and made him drink some diluted with water. He also insisted on taking a course of antibiotics, but I have read that DE will do the trick without the antibiotics. So file that tidbit of information away for the next time you get intestinal parasites {or head lice…}.

DE on cucumbers is an effective and totally organic way to kill cucumber beetles.

Essentially, the way I killed my cucumber beetles was to dump 100% Food-Grade Diatomaceous Earth all over my cucurbits. I lifted the leaves and doused it good on the underneath since the cucumber beetles like to hang out on the underneath side of the plants. And I covered the dirt all around the plants, too. Because despite having read that cucumber beetles don’t crawl around, I see them crawling all over the ground. So I think they do crawl.I tossed some Diatomaceous Earth on my cucumber plants to get rid of those nasty cucumber beetles that kept ruining my crop.The first day I found the cucumber beetles, they were all over. I thought about the situation for a few minutes {because I had to remember WHY I bought that big bag of DE last year…} and headed out to my garden shed. I grabbed the DE and spread it all over using the method I described above.

The next day, I checked on my garden. Instead of finding hundreds of them, I found maybe 10. And I killed them all. The next day, I found ZERO cucumber beetles and I was very encouraged. However, after a few days, 5 maybe, I started finding a few more beetles, so today I covered them all up again with more Diatomaceous Earth since I am going away for 5 days and won’t be able to check on them. It is so helpful to be in the garden every single day to see find stuff like this. I’ve left strict instructions with my husband to be on the lookout for cucumber beetles!

Other organic methods I have read {and tried} for killing Cucumber Beetles:

  • NEEM Oil – this is the first thing I tried. I’m guessing that it didn’t work because I was just too late. I didn’t know right away how destructive they were, and by the time I got the NEEM Oil, it was probably too just late. But it is supposed to be effective.
  • Homemade Trap – it caught a few beetles, but needless to say, I won’t make another one… 😉
  • Row covers – This is something I have not tried yet. Maybe next year.

Cautions I have read about DE –

I read not to use the DE on flowering plants as it also kills the bees that pollinate the plants. A very helpful person on my facebook page told me that I can manually pollinate the plants with a Q-Tip, if need be. One of my plants was already flowering and I am spreading the DE anyway. It does have baby cucumbers on it, so we’ll see what happens.

Otherwise, my garden is growing good. I did find one more bad garden pest on my potatoes, and I will tell you about that soon! But everything else is looking really nice.

My garden is growing well after using some DE to kill the cucumber beetles that kept eating my plants! Have you ever dealt with cucumber beetles? What did you do? And most importantly, how do you stop them from coming back next year? I am really considering burning my garden this year after it’s done.

 How’s your garden growing? Please share! I get sad when they’re aren’t any comments on my blog. 🙁

Linking up: Frugal Days, Sustainable Ways;

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About Michelle

Michelle Marine is green living enthusiast and rural Iowa mom of four. An avid traveler, Michelle has lived on three different continents and has driven all four kids across the entire USA (by herself!). She loves sharing farm-to-table recipes, their family travel adventures, and gardening and homesteading tips on her popular lifestyle blog, SimplifyLiveLove.com.


  1. Michele D. says

    Ooo, will the DE work on ants too do you suppose? Maybe I need to get some. I don’t put down borax because of the cats.

    Do post an update about the beetles when you get back! I am interested in hearing how this works out.

    • Liz says

      They are only good for soil dwelling organisms. I am using DE now. I found them early and only a few a day. I crush a group of eggs under a leaf and the adults when I see them. Just dusted today.

  2. Jim says

    To minimize impact on honey bees, spread the DE in the evening after the cucumber flowers close for the night. The bees to not typically crawl around on the leaves or ground and the beetles do not infest the flowers much.

  3. Ann says

    I tried food grade DE on my plants last summer and it destroyed my 4 pepper plants, and my mint and tomato lost their leaves and had to struggle back. Definitely interfered with tomato production.

    What happened?

      • Paula says

        How often did you have to reapply the DE? How did it work out for the season? I read this today and ran outside to spread the DE as my Zucchinis are affected by the yellow striped bugs. I have DE on hand because I have chickens.

        • Michelle Marine says

          Hi Paula, you have to reapply after a rain or every 4-5 days or so. It works well for a while and then I give up, honestly. It just depends on how badly the bugs have infected your plants before you start. If I catch them quickly and treat early I have much more success than if they get out of hand before I do anything. Good luck!!

  4. Heather says

    What a quick and simple way to get rid of such a destructive insect! Thanks for providing the safety tips for handling DE as well, you definitely don’t want to end up hospitalized for making such a simple mistake. Great guide!

  5. rovin says

    you can try salt. 1 liter water and 1/2 teaspoon of salt. then spray it every morning. Salt is also source of nitrogen and its good for plants

    • Mark says

      Salt is Sodium Chloride, which has no nitrogen at all. Are you perhaps confusing the chemical symbol Na (sodium) with N (nitrogen)? Most plants have tolerance only to a small amount of salt and overdoing it could easily mess up the carefully balanced pathways of water and nutrients in the root system.

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