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Keeping beetles off herbs

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I have a small (2' x 4') herb garden in a raised bed on my back deck. My herbs are doing well, but beetles have arrived. I've hung a couple of beetle traps, but the pests are still making their way to my herbs. I hate to use any kind of spray on them at all, but I'm getting desperate. So I'm wondering, will a spritz of insecticidal soap (homemade) keep the beetles from munching my herbs? Is there something else I should be using? BTW, I'm in southeastern PA (Zone 6, I think). Thanks!

ETA -- Since posting my question a few minutes ago, I've been reading about Companion Planting. It turns out, I may have inadvertently invited these beetles to my garden. I thought marigolds were an insect deterrent, so I planted a few in my herb garden. Then I read this: "...marigolds planted around the border of a garden will deter many insects, and they are especially good at luring Japanese beetles away from your herbs and vegetables. In the morning, you will find hundreds of groggy bugs clinging to the marigold blossoms; pick them off and drop them into a bucket of soapy water." With such a small garden bed, can it be that the marigolds are attracting the beetles, which are then hopping over to my basil, thyme and other herbs?

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  1. The beetle trap may be a bigger problem than the marigolds. Japanese beetle traps attract beetles from quite a wide area and will cause more problems than they solve unless the traps can be located a few hundred feet from target plants. The traps probably are just attracting beetles so they are near the marigolds.

    Quite a few insect pests do not like marigolds, earwigs and Japanese beetles being notable exceptions.

    Insecticidal soaps work mainly for soft-bodied insects that are hit directly by the spray. The soap messes up their oxygen intake.

    Dropping hand-picked insects into a bucket of soapy water works by a somewhat different mechanism. The soap lowers the surface tension of water and facilitates drowning the insects.

    1 Reply
    1. re: Eldon Kreider

      I grow roses and I stopped using the beetle traps 10 years ago because they were attracting beetles more than they were catching them.