Root Weevils - School IPM - USU Extension

    Root Weevils

    Otiorhynchus spp.

    Lilac root weevil

    Lilac root weevil (Entomart, Wikimedia Commons)

    Root weevil

    Strawberry root weevil size comparison (Whitney Cranshaw, Colorado State University, Bugwood.org)

    root weevil

    Root weevil damage to leaves (Whitney Cranshaw, Colorado State University, Bugwood.org)

    Identification

    Larvae

    • up to 1/2 inch long; legless white grub with a brown head capsule

    Adults

    • 1/4 - 1/2 inch long
    • shiny black to shiny brownish black
    • blunt snout

    Nesting Habits

    • larvae develop in soil at the base of host plants
    • adults spend the day at the base of host plants in litter

    Diet

    • larvae: roots of woody shrubs, especially lilac
    • adults: leaf margins of many plants

    Significance

    • adults are common nuisance invaders of homes during late summer and fall
    • can damage leaves and roots of ornamental plants

    IPM Recommendations

    • Use a vacuum and/or sticky traps to collect weevils indoors.
    • Seal cracks, crevices, windows and other areas where weevils can enter.
    • Larvae and feeding adults can be managed outdoors with an appropriately labeled, soil-applied insecticide.