Neem oil and monarch caterpillars?

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  • #14669


    I’m not much of a gardener so I have only just found out about this Neem Oil stuff. I don’t like to fill the forum with my silly questions as I find they can usually be answered in seconds on google without displaying my ignorance to everyone, but this time I am stumped.

    Is neem oil effective against Aphis nerii?

    Is neem oil harmful to monarch caterpillars if sprayed on milkweed?

    Yates say it is harmless to butterflies. I suspect they mean it doesn’t affect the nectar in the flowers, so that isn’t helpful.

    This posting on monarchwatch says it doesn’t harm caterpillars

    But this post on Monarch watch says it does

    This article posted here by Patrick says it is ok

    Its not listed in our aphid fact sheet and Branson hasn’t tried it.

    Does anyone here have any first hand experience with this stuff and Monarch caterpillars?

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    I used Neem granules this year for the first time. A few under each of the brassicas I planted. It has appeared to work well as the plants, athough bitten a little are looking well. The plants take up the Neem chemical and one bite from the caterpillar is the end of it, so I will say a definite ‘no’ to using it near swan plants.



    Hi Jennifer, what sort of soap do you use? People have often suggested dish washing liquid, but that is detergent.
    The good old Sunlight block grated?



    Oh I forgeot to say I wasnt really worried about the citrus because the neem oil works for sap sucking insects so unlikely to effect the butterflys per se but I would never use it on swan plants. There are equally effective methods (eg soap etc -not detergent, thats bad for the soil)



    I cant really help Darren and I have been perplexed too because I use Neem oil particularly against thrips and passionvine hopper in several locations in my garden. I also use it on the citrus. I dont use it though wherever butterflies might sup. As a result I dont use neem oil more generally and use soapy water or soap and rhubarb for more general spraying particularly for aphids (which sometimes infest the swan plants)

    I havent seen butterflys on the citrus flowers, can anyone else comment about that?



    Hi Darren,

    I used Neem granules in potting mix commercially for several years against a number of pests, and although I have not used it as a contact spray on caterpillars, I would avoid it, largely because when I did use it on many species of plants over those years, none of the plants treated ever got a caterpillar.

    I hope that helps……Jane



    I have spoken with Wally Richards (Palmerston North) and he has said not to use it where you have Monarch caterpillars.

    Hope that helps.

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