Gypsy moths are tree pests that damage trees. During outbreaks, gypsy moth caterpillars are a nuisance and can strip trees of their leaves, defoliating neighborhoods or forests by late June. Most healthy trees can survive one such defoliation, but trees that are weak or stressed prior to defoliation may die.
The gypsy moth larvae typically emerge from egg masses in mid-May, grow into caterpillars through June, and then pupate to transform into adult moths around mid-July. The adult moths then mate, leaving egg masses on trees by the end of summer. The tree damage is caused by the caterpillars eating the tree foliage prior to pupation.
Signs of Infestation
Visible egg masses
Fallen/partially chewed leaves
Sounds like rain falling from trees on a clear day
Gypsy Moth Egg Mass
Gypsy Moth Caterpillar
Female Gypsy Moth
Male Gypsy Moth
The ideal time to apply pesticides to infected trees is from early May to late June when the caterpillars are hatched out and eating. There is no need to treat trees unless you specifically see gypsy moth caterpillars. There are no preventative treatments to keep caterpillars from coming to your trees. Preferred hosts of gypsy moths include apple, alder, basswood, hawthorn, oak, poplar, and willow trees. The Village of Roselle recommends that residents hire a licensed and insured pesticide application contractor to treat gypsy moth infestations.