Root weevils on my lilacs' new growth

Asked August 2, 2020, 2:09 PM EDT

I have noticed my new lilac leaves are being eaten by something, and a friend took away a leaf to the nursery, who identified the pest as root weevils. I don't want to do ANYthing to harm my beneficial insects, and have never put poison on anything in my Bend, Oregon, yard. Is there something organic or a household item that would kill or smother the weevils, and not harm good insects and the birds who eat the insects? I thought of SAFER soap, and then wondered idly if Ivory dish soap might not work as well? Thanks for any advice! Suzette in Bend

Deschutes County Oregon

1 Response

From the PNW Insect Handbook there is this summary https://pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/lilac-syringa-root-weevil.

For the pest description: https://pnwhandbooks.org/insect/hort/landscape/common/landscape-root-weevil

From that page there is a pdf download that covers chemical controls, some of which may be OMRI listed for organic use. Root weevils are not soft-bodied insects so are not as sensitive to insecticidal soap that is very effective against pests like aphids. Spinosad is listed as an effective control and is relatively safe (I actually give it to my dog for flea control.) Please be sure to read and follow application directions and safety precautions.