Gypsy Moth

The gypsy moth (Lymantria dispar) was accidentally introduced to the United States in the 1800’s. Originally brought to the U.S. to manufacture silk, it subsequently escaped and has caused extensive foliar damage to a diverse array of deciduous trees. Under wet, rainy conditions, gypsy moth populations can be naturally controlled by a fungus (Entomphaga maimaiga), introduced from Japan in 1910. Recently, there has been a resurgence of gypsy moth populations in the eastern United States, largely due to prolonged, dry springs, which prevented fungal establishment.

Gypsy moth is a forest and urban pest in the eastern United States. Caterpillars feed on a multitude of tree species, and when they reach high population densities, they will feed on almost any tree or shrub. Their preferred species include oak, maple, beech, birch, hawthorn, apple, poplar, and willow.

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  • Common Symptoms
    • Dark colored, hairy caterpillars with 5 pairs of blue and 6 pairs of red dots lining their back can be seen in May and June. White female and brown male moths are active throughout July and August. The caterpillars are responsible for tree damage, feeding on foliage and stressing the tree. Trees that are completely defoliated may re-foliate 3-4 weeks after feeding ends; however, this requires the trees to expend an enormous amount of energy. As a result, repeated defoliations may kill the trees or severely weaken them, making them vulnerable to secondary mortality factors.

    Treatments
    • Trunk injection with any of the TREE-äge® family of products and Mn-jet Fe™ will provide both preventative and curative control depending on the time of year treatment is applied. We recommend treatment in late September, which will minimize early pest damage the following spring.

    References And Photo Credits
    • Main photo taken by USDA Forest Service – Region 8 – Southern
      Damage taken by John Ruter, University of Georgia, Bugwood.org
      Egg Masses taken by Cifáre/Slovakia

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