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Flea beetles

Bok choi under row cover

All of the brassicas, except for radishes, start out under floating row cover. It’s the only way they’ll survive the flea beetles. Around here, the FBs are a clear and present menace to the cabbage family. They chew little holes in tender baby leaves until nothing but stems and dried out leaf skeletons remain. It’s awful. I could use organic sprays, like rotenone or pyrethrin, but although they’re “approved” and from natural sources (other plants), it seems to me a slippery slope, or at least habit-forming. I haven’t sprayed so far. I did try a garlic blender concoction as a repellent once, but it was like cooking for the FBs, they hopped off and hopped back on once the spraying stopped: salad dressing! Anyhow, this is bok choi (pak choi). FBs eventually managed to get under the edges and do a bit of damage, but that’ll be outgrown, bok choi grows fast (as do radishes). Once the leaves get a bit more substantial, the FBs can’t as easily chomp on ’em. Cauliflower and broccoli, under this same 14′ wide sheet of row cover, are untouched. FBs REALLY like bok choi!



  1. Funny, I walked into my garden just today to find this same kind of damage on my eggplants and tomatoes. Since I read your post earlier today I was able to look up FBs and confirm that that’s what I’ve got. Thanks for identifying them for me, at least!

  2. Jenny: Yikes. When you look up these pests, besides their main interests, there’s usually quite a list of other crops they’ve been known to devour. Luckily, my regulars are conservative: the FBs stick to the brassicas and don’t include tomatoes, spinach or whatnot, the Colorado potato beetles stick to potatoes (and don’t hop over to eggplant or tomatoes), the cucumber beetles stick to the cucurbits (and ignore the peas, beans, etc). Yours seem to be more adventurous… Oooh. Doesn’t bear thinking about too much! :)

  3. Wilbur

    Anyone know what companion plants would keep the flea beetle off arugula? Nothing mentioned in Carrots Love Tomatoes.

  4. Wilbur: At least around here, flea beetles LOVE arugula, so if you have FBs and you grow organically, with no spraying, you’ll probably need floating row cover. If you take care to keep the edges of the cover pretty well pinned down, it does the trick with all brassicas. As far as a trap crop, mustard is an inexpensive brassica that FBs really like. They also seem to particularly favor bok choi. I haven’t experimented much with FB trap crops, but I imagine in smaller gardens, they won’t entirely distract FBs away from the crop you’re trying to protect, just lessen the attack.

  5. Sheri

    I went down to the brassica rows yesterday to see how far along my beautiful just-starting-to-head broccolis were doing and oh, what is that? Black brassicas? Yes, the flea beetles are back, and with a vengeance. I am so disappointed as I only just uncovered the cabbage about a week ago to give it more light as it was struggling under the row cover. I never did get the cover on the brocc and cauli b/c there were no beetles around when I transplanted them and I (stupidly) thought, well they’re gone for now and won’t be back before the plants are spent. Was I wrong. When I left the garden today I looked back on the broccoli and most of the leaves were brown and eaten and I’m very sad. Sad too for my CSA sharers b/c I promised broccoli on Monday. As an aside, they’ve just started to harvest around here, which means the canola too, and I can’t help but wonder if all the beetles have jumped from the fields to my garden, even though there was no canola in the fields next to me. Was so looking forward to that organic broccoli!!!! Now I know why people spray things. Very :(

  6. leah

    i just started to plant some Bok-Choi and lack of experiences about FBs. Yesterday, I had seen  a tiny black beetle, i guess it’s FB. But, under the leaves, i also found many small tiny black spots. Is it egg or something else?

  7. leah

    tq. netting did help me very much. but i’m still too curious to know about that small black spot under the leaves. so i just left a few bok-choi uncovered and found those things few days later. i cut the leaves and and washed them with water. those black spot can be easily removed. i guess they are FB’s eggs but kinda weird because they scattered all over the leaves..

  8. aaron

    My guess would be that they are fb excrement, yes it would be a good idea to wash those off.

  9. I always see this kind of holes in cabbages. I was even able to see them on my dad’s garden. Are they also the one’s causing holes to other veggies? 

  10. Probiotics

    That one sure does look scary. I do see those wholes in some leafy vegetables. They are ruining a picturesque and delicious vegetable. However, one can also understand that those fleas are also doing(eating veggies) to survive. 

  11. Rabbit Hutch

    I have seen this one plague one of our leafy vegetable way back in our province. However were still finding some solutions for this without using any pesticides since it may lead to some problems with the health.

  12. luxxnatura

    I battled FBs on my bok choi and mustard greens also… tried many different organic remedies (companion planting parsley and dill, garlic sprays, soap sprays) but the only one I found that worked (and quite well, I might add) was wood ashes. I got some from someone’s fire place by asking around on some local mailing lists. It’s great and I will use it from hereon out!

    • Mark Mazur

      Q for luxxnatura: we’ve been looking for a good organic solution to flea beetles as they enjoy decimating our bok choy and eggplants. Using wood ash sounds very interesting… do you dust the plants with it, do you sprinkle it around them on the ground? Both? Let us know…sounds like a great potential solution whih we’d like to try promptly.
      Mark Mazur, LangdonFarmsNY

  13. steph

    proteknet is the business for flea beetle protection, for sure. and the folk at dubois are super helpful and well informed.
    i used the 80 gram on salad mix production, field scale and it worked well. and it worked on radishes and salad turnips too… much better than trying to battle with remay,,, better light to the plants and air circulation..
    i havent used the 25 gram.

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