Euonymus Scale

    Euonymus Scale

    Unaspis euonymi

    euonymus scales

    Euonymus scales; note brown females and white males  (Lisa Ames, University of Georgia, Bugwood.org)

    euonymus scales

    Euonymus scales (Edward L. Manigault, Clemson University, Bugwood.org)

    euonymus scales

    Euonymus scales (Joseph LaForest, University of Georgia, Bugwood.org)

    Pest Description

    • males: 1/16 inch; white, oysterlike hard scales
    • females: longer and wider than males; mottled brown
    • immatures: crawlers (mobile stage) 3/64 inch; yellow orange; no wings
    • immatures: nymphs (sessile stage) resemble adults, but are smaller

    Host Plants, Diet & Damage

    • Euonymus, Camellia, boxwood, bittersweet, Daphne, Eugenia, ivy, Hibiscus, holly, jasmine, privet, honeysuckle, olive, Paxistima, Pachysandra, Solanum and Prunus
    • feed on leaves (mostly on the undersides) and stems
    • males are typically found on the undersides of leaves; females mostly found on stems/petioles
    • create yellow-white spots on leaves
    • scales covering stems appear bumpy, corky or frosted
    • feeding can cause thinning, leaf drop and plant death
    • damage is often worse when plants are located near buildings/walls/etc.

    Biology, Life Cycle & Damaging Life Stage

    • overwinter as fertilized females or male pre-pupae
    • males molt into flying insects and mate with females
    • eggs laid in early spring (May to June) under the female
    • crawlers present late-May to June and July to October
    • crawlers disperse via crawling or wind currents
    • there are two generations per year, but life stages overlap
    • nymphs and adults are the damaging stages

    IPM Recommendations

    • Keep trees healthy.
    • Monitor scale populations on host plants (e.g., Euonymus).
    • Non-synchronized life cycle makes crawler control with foliar-applied insecticides difficult.
    • Apply a systemic dinotefuran soil drench, granules or bark band in May. Imidacloprid is ineffective against hard scales.