Again this year, gypsy moth infestations have been found in Wood County.
The introduction of the gypsy moth into the United States is a great example of an experiment gone
extremely wrong. Native to Europe and Asia, the gypsy moth was brought into Medford, Mass., in 1869 by
E. Leopold Trouvelot, a French artist and amateur entomologist, looking to develop a new strain of
silkworm for silk production.
He was culturing egg masses on trees in his back yard when some larvae (caterpillars) escaped into the
surrounding community. Local entomologists were notified, but no action was taken to eradicate the pest.
The first outbreak of the gypsy moth occurred on Myrtle Street, in Medford, in 1882.
Since the first escape, the gypsy moth has advanced throughout various areas including the Great Lake
states and Canada despite control efforts and natural enemies.
In Ohio the first male moths were trapped in Ashtabula County in 1971. Today, 46 counties including Wood
County in Ohio are under the quarantine regulations.
The gypsy moth completes one life cycle (four stages) per year.
1. Egg: Eggs are laid in a hairy like, brownish tan mass in late July thru early September. The size of
each egg mass ranges from 1 to 1 1/2 inches in length. The number of eggs in each mass can range from
500 to 1,000. They remain in this stage until April to early May. Egg masses are often laid in sheltered
areas of trees, buildings, fire wood, outdoor furniture, lawn equipment, and even rocks.
2. Larvae: In mid April, or about the same time Eastern Redbuds are starting to bloom tiny larvae will
begin emerging from the egg masses. They will begin to move up into the tree canopy and start feeding on
the leaves. The larvae continue to grow by molting. After each molt the larvae moves into its next stage
known as an instar. Feeding occurs mainly at night and during the daylight hours they usually seek
shelter from the sun. But under heavy infestations feeding can go on around the clock. The larvae stage
is the only period in which damage is caused to the trees by leaf feeding during the pests’ life cycle.
This stage lasts approximately six weeks.
3. Pupa: In early to mid-June the larvae will stop feeding, shed their skins for the last time and
pupate. While in the pupa cases they transform into moths. This process usually takes about two weeks.
4. Moth: In late June, early July the moths emerge from the pupa cases. Their only mission is to mate and
lay eggs. Since the female does not fly, she has to put out a pheromone scent to attract the males to
her. Once they mate and lay their egg, the moths die. This stage lasts approximately two weeks.
How much defoliation an area experiences depends on the gypsy moth population level, tree species
composition, and the quality of larval hiding places.
Areas that contain a high proportion of preferred species are more likely to be defoliated than those
with more species variability. An area that contains more than 250 egg masses per acre can expect
Individual tree responses to defoliation will be affected by the amount of defoliation and the tree’s
over all health. With broadleaf deciduous trees, light defoliation will weaken but usually not kill a
tree. However heavy defoliation, or trees with less vigor are more susceptible to secondary pests like
insects and disease.
Repeated annual defoliation will result in the death of the tree. Conifers such as pines, spruce, fir,
etc., often die the first year as the result of the initial heavy defoliation, because they are unable
to produce a second set of leaves.
To put things into perspective, one 2-inch larvae will consume 1-square foot of foliage every 24 hours.
When you have 500 to 1,000 larvae emerging from a single egg mass and have 250 or more egg masses per
acre, this pest becomes one big eating machine.
In Ohio Gypsy Moth larvae have a high feeding preference for ornamental crab apples, both white and red
oak, hawthorn, witch-hazel, river birch, spruces, and sweetgum. When food sources become scarce they are
also known to feed on beech, serviceberries, maples, walnuts, hemlocks, cottonwoods, cherry, and white
In the event your trees are attacked by gypsy moth keep your trees and shrubs healthy. Should defoliation
occur, irrigate affected trees and shrubs. Adequate water will help in the recovery process. Avoid
nitrogen fertilizer as this will encourage leaf growth at the expense of building food reserves to the
(The Ohio Department of Agriculture contributed to this story.)
Dealing with gypsy
Dorothea Barker of Bowling Green asks: Gypsy moths have been found in my neighborhood. What can I do to
protect my oak trees?
According to Craig Everett with Ohio State University Extension, here are some things which can be done
in areas that have gypsy moths. Those who have problems can use these control measures to help lessen
¥ Scrape egg masses and pupa cases off buildings, trees, shrubs, or any outdoor items and destroy them by
submerging them in soapy water for at least two days. Egg masses can also be killed by spraying them
with horticultural spray oil labeled for gypsy moth.
¥ Collection bands, 12 to 18 inches wide, made of burlap, wrapped around a tree, and folded over to make
a skirt attract larvae looking for shade during the day. Each day you will need to remove and destroy
¥ Pheromone traps can be placed to attract the male moths and prevent them from mating with the females.
Some traps contain soapy water in the bottom to kill the moths and some contain an insecticide strip.
¥ Chemical treatments are most successful when applied to the foliage during the larvae’s early instar
stages. Trees and shrubs can be treated with a biological pesticide like Bacillus thuringgiensis (Bt) or
with chemical pesticides labeled for gypsy moth. These products are available at your local garden
center or nursery. Please read and follow all label directions.
If you live in the quarantine area of the state and your area has been heavily infested with gypsy moth
you and your neighbors may qualify for the State of Ohio Suppression Program. The state suppression
program is aerial treatment administered through the Ohio Department of Agriculture. Areas to be treated
needs to be 50 acres or more.
For help in Wood County contact your local OSU Extension Office at (419) 354-9050.