The gypsy moth (Lymantria dispar) is one of the most destructive insect pests threatening our forests, trees and shrubs.  It was introduced more than 100 years ago, and has slowly munched its way west and south from its original infestation point in Massachusetts.

The gypsy moth develops in four stages:

and has only one generation per year.  It overwinters in the egg stage in tan-colored masses.  Hatching generally occurs in late April or early May, just as tree leaves are emerging.  The newly hatched larvae are 1/8" long, hairy, and mostly dark brown to black.  They climb to the tops of the trees and feed on leaves.  The larva spins a thread and uses wind currents to balloon from tree to tree.  This is the main way gypsy moths disperse.

Gypsy moth larvae will feed on 500 species of plants, but oak leaves are preferred.  Other species include:  apple, basswood, aspen, river birch, mountain ash, sweetgum, willow, hawthorn, roses, serviceberry and witch hazel.  Deciduous trees are weakened by severe gypsy moth defoliation making them more susceptible to other stresses such as drought, diseases, and other insects.  Evergreen plants are often killed after one year of defoliation.
 

In late June or early July, the larvae finish feeding and find a sheltered place to pupate.  The 1/2" to 1" pupa, or resting state, is hairless and dark brown.  Pupation takes two weeks and adult moths emerge in July or August.

Male moths emerge first and fly in a zigzag pattern during daylight hours.  Females do not fly, but can crawl a short distance.  Adult moths do not feed.

Improve your tree's health through good tree care practices.  Choose the right plant for the right place, thoroughly water plants during dry periods, fertilize regularly, avoid injury to the bark, and selectively prune branches that are dead, dying, and/or rubbing together.  Introduce new plants that are disease and insect resistant.  To reduce plant loss, plant a wide variety of species.

When the Ohio Department of Agriculture (ODA) egg mass survey is complete, approximately December 15th, hand pick and destroy egg masses from tree trunks and other outdoor surfaces, such as picnic tables and chairs, recreational vehicles, eaves, and overhangs.  Destroy by burying them 6-12" in the soil.  The masses can be the size of a quarter, and are tan and fuzzy.  Each egg mass may contain as many as 1,000 eggs.

Wrap a 1 1/2' - 2' band of burlap or other thick material around the tree trunks, tie a cord around the middle and let the upper flap drop down.  As caterpillars crawl up and down the trees during their nightly feedings, they will hide in the band during the day and can be collected and destroyed by placing them in soapy water.  This method requires daily maintenance.

Sticky substances applied to bands of tape, foil or other material can also be used as a trap.  (Do not place the sticky substance directly on the trunk.)  This method is not as effective as the burlap wraps, since the insects prefer to hide in the burlap folds during the hot part of the day.  This also requires regular maintenance.

Bacillus thuringiensis var. kurstaki (Btk), a naturally occurring bacteria, applied as a spray in the early stages of the caterpillars' growth cycle has proven to replace populations.  Specific to small larvae, it is not harmful to people, pets, birds, bees, and most other insects.

A fungal pathogen, Entomophaga maimaiga, has dramatically reduced the number of gypsy moths.  The fungus requires high rainfall and humidity to spread.  The fungus has been distributed throughout Lucas County.

Nucleopolyhedrosis (NPV), a virus found in nature, is being produced by the USDA Forest Service to control the gypsy moth.  It has proven most effective when used on large, stressed populations of the gypsy moth.  Supply is limited.  It is not available for homeowner use.

Broad spectrum insecticides (made for use on a wide range of plants and a variety of insect pests) such as Carbaryl, Dimilin, Orthene, Sevin, Talstar, Tempo, and Turcam are all labeled for control of the gypsy moth.

All chemical controls, including biological controls such as Btk. require trained, licensed pesticide applicators to be applied correctly.  Pesticides pose an environmental hazard when used incorrectly.  Pesticides should be used only when cultural controls (i.e.: burlap bands, egg mass collection, and hand picking) fail to control the gypsy moth populations.

The gypsy moth is here to stay in Northwest Ohio.  Just as we have learned to live with other insects, such as the Japanese Beetle, we need to learn to live with the gypsy moth.  For additional information contact Amy Stone, Extension Agent, Consumer and Urban Horticulture - Lucas County at 419-243-MOTH (6684).
 
 
 

All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.

Keith L. Smith, Associate Vice President for Ag. Admin. and Director, OSU Extension.  TDD No. 800-589-8292 (Ohio only) or 614-292-1868