Leafminers and Needleminers

    Leafminers and Needleminers

    Coleoptera; Diptera; Hymenoptera; Lepidoptera

    leafminer

    Adult birch leafminer (Cheryl Moorehead, Bugwood.org)

    leafminer damage

    Birch leafminer damage Brian Kunkle, University of Delaware, Bugwood.org)

    leafhopper damage

    Spruce needleminer damage (Steven Katovich, USDA Forest Service, Bugwood.org)

    Pest Description

    • adult leafmining insects include small beetles, flies, sawfly wasps or moths
    • larvae are tiny grubs/caterpillars that fit between the upper and lower leaf tissues
    • feeding causes telltale patterns in leaf tissue

    Host Plants, Diet & Damage

    • leafminers: many deciduous tree species
    • needleminers: many coniferous tree species
    • larvae feed on mesophyll cells on the interior of the leaf
    • larval feeding creates silvery white blotches or tunneling in the leaf
    • mining may turn leaves brown and translucent
    • larval frass is typically present in the galleries
    • damage is an aesthetic issue and rarely harms trees

    Biology, Life Cycle & Damaging Life Stage

    • life cycles are highly variable
    • larvae may pupate in the leaf or in the soil below plants
    • eggs laid in small groups or singly on or in plant tissue
    • one or more generations occur every year, depending on the species

    IPM Recommendations

    • Manage trees to improve or maintain overall health.
    • Pesticide applications are not typically needed for leafminers and needleminers.
    • Predators and parasitoids typically manage larvae.
    • Apply an insecticide (azadirachtin; neonicitinoid; pyrethroid; spinosyn) to foliage just prior to egg laying.
    • Apply a systemic neonicitinoid as a soil drench after leaf expansion in spring.