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Gypsy Moth Program

gypsy moth larva

General Information

The European gypsy moth (Lymantria dispar) is a non-native, invasive species that has moved into Ohio from Pennsylvania and Michigan over the years. In its caterpillar stage, it feeds on the leaves of over 300 different tree and shrub species and is especially fond of oak. A healthy tree can usually withstand only two years of defoliation before it is permanently damaged or dies. To date, 51 of Ohio's 88 counties have established gypsy moth populations.Gypsy moth population map

The Ohio Department of Agriculture operates three programs aimed at managing the gypsy moth in Ohio. These three programs mirror the three zones defined in a spreading infestation. In the infested zone, the moth population is well established and colonies overlap. The second zone is the transition zone, in which isolated populations have developed but are not generally overlapping. The third zone is the uninfested zone, in which no pest populations have developed.

The damage from gypsy moth comes during its larval form. One 2 inch larvae can consume up to 1 square foot of foliage every 24 hours; each egg mass can contain 500 - 1000 eggs. In heavily infested areas, where there is 250 or more egg masses per acre, larvae can defoliate the infested trees. Repeated annual defoliation can result in the death of the tree.

Preferred Tree Species (Native to Ohio)
High preference: American crab apple, American hophornbeam, Bigtooth aspen, Black oak, Bur oak, Chinkapin oak, Red oak, Scarlet oak, Shumard oak, White oak, Cockspur hawthorn, Common witch-hazel, Eastern larch, Pussy willow, River burch, Smooth sumac, Staghorn sumac, Sweetgum.


Ohio operates three programs to control the gypsy moth population:

  • The Suppression Program (in the infested zone) is in areas where the gypsy moth is well established and treatments are performed at the voluntary request of the landowners. 
  • The Slow-the-Spread Program (in the transition zone) focuses on monitoring, detecting, and reducing isolated populations to slow the gypsy moth's natural movement across the state.
  • The Eradication Program (in the uninfested zone) focuses on monitoring and detecting any populations that may have jumped out ahead of the transition zone, due to artificial movement. Treatments are so designed to "eradicate" the isolated populations.


Click here for the Suppression Treatment Application package:

ODA's Gypsy Moth Suppression Program began in 1989.  Because the gypsy moth is already established in 51 counties in Ohio, the goal of the suppression program is not to eliminate the moth, but to protect trees and reduce defoliation in these areas.

This program is coordinated and funded by ODA, USDA Forest Service and private landowners wishing to participate through a 50/50 cost share.  This program is strictly voluntary. 

Landowners may request the state apply an aerial treatment for the gypsy moth by submitting an application through a "block coordinator" in late summer (deadline is Sept. 1).  ODA staff will then conduct a survey to determine if treatment block meets the criteria for suppression treatment.

Treatment criteria:

  • Proposed block must be located in a county that has been designated quarantine for gypsy moth by ODA.
  • Proposed block must contain a minimum of 50 contiguous forested acres.
  • Proposed block must have a concentration of at least 250 egg masses per in residential forested areas or 1000 egg masses per acre in uninhabited forested areas.
  • Proposed block must have a tree canopy that covers no less than 50% of the block.
  • Proposed block must consist of at least 35% of tree species that are either susceptible or slightly resistant to the gypsy moth.
  • Proposed block must receive a favorable T & E Assessment from ODNR and the US F & W Service.

Once approved, cost share payment from the landowners will be due by March 1 of the treatment year.

Treatment options include Btk, Gypchek, Diflubenzuron, and Tebufenozide.

Slow the Spread (STS)

The Slow the Spread Program is a national strategy funded by the USDA (Forest Service and APHIS) and State cooperators that lie along the leading population edge.  The purpose of STS is to reduce the overall rate at which the gypsy moth spreads into uninfested areas.

Ohio, which is located along this leading edge, implements STS by deploying pheromone traps (delta and milk carton) to monitor movement; evaluate, detect or delineate newly established colonies and then conducts treatments to slow the spread. Approximately 12,000 traps are set each year in Ohio. 

Trap catches above a certain threshold triggers more intensive trapping the following year to help delineate the location and extent of infestation.  In the third year, some measure of control is taken. 

Treatment options include mating disruption, Btk, Gypchek, Diflubenzuron, and Tebufenozide.

More information about the STS program can be found at the Gypsy Moth Slow The Spread Foundation.


The Eradication Program deals with isolated gypsy moth populations that arise beyond the transition area in what is considered the non-infested zone. These populations develop as a result of human movement of gypsy moth life stages on infested material such as fire wood or other outdoor materials from outside the area. The objective is to eradicate these small isolated populations before they can establish themselves.

Funding for the Eradication Program comes from USDA – APHIS / PPQ and the state cooperators.

Treatment options include Btk, Diflubenzuron and Tebufenozide.

Treatment Materials

General information about the pesticide treatments available for the Ohio Department of Agriculture to use in treatment gypsy moth infestations.

Foray 48B, Foray 76B, Bacillus thuringiensis v. kurstaki (Btk)

Bacillus thuringiensis v. kurstaki (Btk) is a naturally occurring bacterium found in soils across the world. The insecticidal properties of Btk are specific to caterpillars of certain moths and butterflies. Btk spores and protein crystals are ingested by the gypsy moth caterpillar along with foliage. Enzymes in the mid-gut of the caterpillar dissolve the crystals and release delta-endotoxins, which are insecticidal crystal proteins. The proteins bind to specific receptors on the cellular lining of the midgut and penetrate the cell membrane. The insect stops feeding and dies within a few hours or days.

Gypchek, Nucleopolyhedrosis virus (NPV)

NPV is a naturally occurring virus that attacks specifically the gypsy moth caterpillar. Gypchek must be ingested by the gypsy moth caterpillar. The virus multiplies rapidly in cells of the insect and eventually causes breakdown of internal tissue and death. The entire process takes 10 - 14 days, depending on the size of the caterpillar, viral dose, and ambient temperature.

SPLAT, Disrupt II, Disparlure (Mating disruption)

Pheromones are chemicals produced by insects and used in communication. Disparlure is the gypsy moth pheromone that attracts male moths to female moths for mating. Synthetically produced disparlure can be used to disrupt the mating of gypsy moths. Instead of luring adult male gypsy moths away from females, application of disparlure interferes, or “disrupts,” the male moths’ normal mate search behavior, which prevents them from finding females and mating with them. Disrupt II and SPLAT both contain the synthetically produced disparlure.

Mimic 2LV, Tebufenozide

Tebufenozide is an insect growth regulator that imitates the natural insect molting hormone thus initiating a premature and lethal molt in the gypsy moth larvae. Upon ingestion of tebufenozide, larvae stop feeding and undergo an early, incomplete and lethal molt.

Dimilin 4L, Diflubenzuron

Diflubenzuron is an insect growth regulator that works by preventing the formation of chitin, an important structural component of the outer skin of gypsy moth larvae. The caterpillar cannot complete the molting process, its body wall ruptures from internal pressure, and the insect dies. Ingestion of diflubenzuron is lethal to the gypsy moth caterpillar.

Open Houses

Open Houses are informal meetings where people can get information about the upcoming gypsy moth treatment project.

Due to COVID-19 precautions, 2021 open houses will be conducted by video conference. Links to the virtual open houses will be available one week prior on the homepage of agri.ohio.gov.

Please see the attached document for location details on upcoming Open House sessions.

2021 GM Open House Webinar Dates and Focus Areas

Monday, February 8, 2021 6:00 pm
• Athens, Hocking, Noble, Vinton, Washington Counties
Belpre MD, Macksburg MD, Mineral MD, South Bloomingville Btk/MD, South Bloomingville MD
Tuesday, February 9, 2021 6:00 pm
• Licking County
Jersey Btk/MD, Jersey MD, Granville MD, Hickman MD, Newark MD, Toboso MD
Wednesday, February 10, 2021 6:00 pm
• Delaware, Knox, Morrow Counties
Centerburg A MD, Centerburg B MD, Homer MD, Sunbury MD
Thursday, February 11, 2021 6:00 pm
• Seneca County
Tiffin South Btk/MD, Tiffin South NPV/MD, Tiffin South MD
Monday, February 16, 2021 6:00 pm
• Auglaize, Hancock, Wood Counties
Arcadia A MD, Arcadia B Btk/MD, Arcadia B MD, Cygnet MD, Wapakoneta MD

Treatment Map

aerial application of pesticidesEach summer the Ohio Department of Agriculture deploys approximately 12,000 gypsy moth traps across the state to monitor movement and evaluate, detect or delineate newly established colonies. Proposed treatment areas are determined in the fall prior to the treatment year, based on the catch numbers and the available funding between the state cooperators. Products and application rates are determined based on the catch numbers and other environmental factors.

treatment map thumbnail

Treatment Dates

The grid below shows the expected dates when treatments are to occur and when they were completed. Please note that treatments of individual blocks are dependent on larvae and oak leaf development and are subject to change based on weather conditions. Larvacide treatments are typically conducted during May, and mating disruption treatments occur during mid-June. Treatments that have yet to be scheduled will be listed as “To Be Announced” (TBA). Call 614-387-0907 for the most current schedule.

 Area Name County Product  Scheduled Treatment
Arcadia B BTK-MD Hancock Valent 48B May 13 Completed
Jersey BTK-MD Licking Valent 48B May 12 Completed
South Bloomingville BTK-MD Hocking Valent 48B May 12 Completed
Tiffin South BTK-MD Seneca Valent 48B May 13 Completed
Tiffin South NPV-MD Seneca Gypchek May 13 Completed
Arcadia A MD Hancock SPLAT June 18-22 Completed
Arcadia B MD Hancock SPLAT June 18-22 Completed
Belpre MD Washington SPLAT June 18-22 Completed
Centerburg A MD Knox SPLAT June 18-22 Completed
Centerburg B MD Knox, Morrow SPLAT June 18-22 Completed
Cygnet MD Wood SPLAT June 18-22 Completed
Deavertown MD Morgan, Perry SPLAT June 18-22 Completed
Granville MD Licking SPLAT June 18-22 Completed
Hickman MD Licking SPLAT June 18-22 Completed
Homer MD Knox SPLAT June 18-22 Completed
Jersey MD Licking SPLAT June 18-22 Completed
Macksburg MD Noble SPLAT June 18-22 Completed
Meeker MD Wyandot SPLAT June 18-22 Completed
Mineral MD Athens, Vinton SPLAT June 18-22 Completed
Newark MD Licking SPLAT June 18-22 Completed
South Bloomingville MD Hocking SPLAT June 18-22 Completed
Sunbury MD Delaware SPLAT June 18-22 Completed
Tiffin South MD Seneca SPLAT June 18-22 Completed
Toboso MD Licking SPLAT June 18-22 Completed
Wapakoneta MD Auglaize SPLAT June 18-22 Completed

Home Practices

There are several practices homeowners can employ if a gypsy moth infestation is found: 

Cultural Practices

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 they will encourage leaf growth at the expense of building food reserves in the roots.

Do not move outdoor lawn furniture, garden equipment, or fire wood without first inspecting the items for gypsy moth life stages.  If moving to a new area, check to see if you are required to follow quarantine regulations of this state or any other state.

Physical Practices

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 or by burning them.  Egg masses can also be killed by spraying them with a spray oil labeled for gypsy moth.

Barrier bands can be placed around tree trunks to prevent larvae from climbing back onto the trees.  Place a non-porous material around the tree trunk and coat it with a commercially available sticky material.  Never apply the sticky material directly to the tree trunk.  The larvae will become entangled in the sticky material and die.  The sticky material will need to be re-applied periodically.

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 the larvae.  Recently, collection band products have come onto the market that contain an insecticide in the band that kills the larvae.

Chemical Treatments

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 the area needing to be treated is 50 acres or more, then you and/or your neighbors can apply for an aerial treatment through the Suppression Program.

For help in your area, contact your local certified arborist, OSU Extension Office, or ODNR Urban Forester.

Life Cycle 

The gypsy moth completes one life cycle (4 stages) per year.Gypsy moth life cycle


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 1000. They remain in this stage until April to early May. Egg masses are placed in sheltered areas of trees, buildings, fire wood, outdoor furniture, lawn equipment, and even rocks.

Images of the egg mass stage


In mid-April, tiny larvae (1/8 inch) will begin emerging from the egg masses. After emerging they begin to move up into the tree canopy and start feeding on the leaves. Larvae will molt 5-6 times before they reach adult size (2 to 2 1/2 inches). Feeding occurs during the periods between moltings (instar) and is mainly at night. Under heavy infestations feeding can go on around the clock. The larval stage is the only period in which damage is caused to the trees (leaf feeding) during the pest's life cycle. This stage lasts approximately 6 weeks.

Images of the larva stage


In early 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 2 weeks.

Images of the pupa stage

Adult Moth

In late June thru early July the moths emerge from the pupa cases.  Usually the males will emerge first followed by the females.  Their only mission is to mate and lay eggs. They do not feed during this stage. 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 2 weeks.

Images of the adult moth stage


Spread and Damage


The European gypsy moth spreads in two ways, either by natural or by artificial dispersal.

Natural dispersal occurs when newly hatched caterpillars hang from tree branches on silken threads, allowing themselves to be picked up in the wind. The wind can carry them for several hundred yards to a mile, to reach another food source. This is called ballooning. As the caterpillar grows larger, their mode of transportation changes to crawling from one food source to another.

Artificial dispersal occurs when people inadvertently transport one of the life stages from an infested area on a car or recreational vehicle, lawn furniture, firewood, logs, nursery stock and other outdoor items. Before leaving an infested area, check your outdoor items to be sure you are not taking any hitch-hikers with you.


The impact gypsy moth will have on a particular forest stand depends on how much defoliation occurs in the stand and how well the trees in the stand can tolerate that level of defoliation.  How much defoliation a stand experiences depends on the gypsy moth population level, tree species composition, and the quality of larval hiding places.  Egg mass counts in excess of 250 per acre generally indicate that a noticeable defoliation is imminent.  Stands that contain a high proportion of preferred species are more likely to be defoliated than those with more species variability.  Stands that contain numerous larval hiding places should support higher population levels, and thus experience more defoliation.

Individual tree responses to defoliation will be affected by the amount of defoliation and the tree's overall health.  With broadleaf deciduous trees, light defoliation will weaken but usually not kill a tree.  Heavy defoliation (> 50%) will often cause them to lose their remaining leaves and develop a second set of smaller, less efficient leaves.  Weakened, less vigorous trees are more susceptible to secondary pests (insects and disease).  Repeated annual defoliation will result in the death of the tree.  In contrast, conifers (pines, spruce, fir, etc.) often die as a 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 1000 larvae emerging from a single egg mass and have 250 or more egg masses per acre, this pest becomes one big eating machine.

Adverse Effects of Defoliation and Mortality

On People

  • Loss of shade, causing increased heating and cooling cost.
  • Decrease property value due to loss of aesthetics.
  • Safety hazard due to dead trees and the expense of tree removal.
  • Skin rashes or irritations, development of allergies in sensitive individuals because of contact with the pest.
  • Caterpillars and their frass (droppings) staining homes and sidewalks.

On Environment

  • Decline in tree health.
  • Increase tree mortality.
  • Increase in fire danger.
  • Increase in stream temperatures.
  • Decrease in aquatic life.
  • Reduction in food supply for small animals (nuts).
  • Decrease in population of small animals (squirrels).
  • Reduction in food supply for some song birds.
  • Increase in nest predation of song birds due to lack of cover.
  • Increase in nesting failures of grouse and turkeys.
  • Migration of turkey and deer to non-defoliated areas.


Introduction of the Gypsy Moth in the United States

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, Massachusetts 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, Massachusetts in 1882.  Since the first escape, the gypsy moth has advanced throughout the New England states, south to North Carolina, and west through portions of the Great Lake states and Canada despite control efforts and natural enemies.

Introduction of the Gypsy Moth in Ohio

The first male moths were trapped in Ashtabula County in 1971.  Two years later, 1973, the first chemical treatments were implemented to eradicate localized populations.  Between 1973 and 1987, eradication efforts continued, but populations still grew.  In 1987, Ashtabula County became the first county to have gypsy moth quarantine regulations imposed on it.

In 1989, the Ohio Department of Agriculture in conjunction with the USDA-Forest Service initiated the Gypsy Moth Suppression Program.  This program continues today as a way for landowners in areas considered generally infested to voluntarily receive assistance in suppressing this exotic pest.

In 1998, pheromone traps were placed over the entire state of Ohio in an 8 kilometer grid system to estimate the infestation densities across the state.  With this information an infestation line (10 moth line) was drawn, with the area to the east of this line being considered generally infested.

In 1999, the Slow the Spread Program was added by the USDA (Forest Service and APHIS) in Ohio as a means of monitoring the advancement and to eradicate isolated populations ahead of the infestation line.  A 100 kilometer swath, paralleling the infestation line to the west was established and is referred to as the STS Action Zone.  Monitoring and treatment projects continue today.

The gypsy moth is a non-native, invasive species that has moved into Ohio from Pennsylvania and Michigan over the past decades. In its caterpillar stage, it feeds on the leaves of over 300 different tree and shrub species and is especially fond of oak. A healthy tree can usually withstand only two years of defoliation before it is permanently damaged or dies.


Currently 51 counties in Ohio are regulated under the Gypsy Moth quarantine. Gypsy Moth regulated articles include, but are not limited to:

  • trees and woody shrubs, including cut Christmas trees;
  • logs, pulpwood, slab-wood, firewood, and wood-bark chips
  • outdoor household articles, including: tables, doghouses, planters, garden equipment, playhouses recreational vehicles
  • other products or articles, or means of conveyance that may carry a life stage of the Gypsy Moth

Producers who ship nursery stock out of regulated areas to non-regulated areas must have their stock inspected and each load must be accompanied by a certificate which attests to the fact that their product is free of gypsy moth.  Producers, who make repeated shipments, are urged to take steps necessary to qualify for a "Gypsy Moth Compliance Agreement" and master certificate, otherwise, they will face delays in obtaining certificates.

Compliance Agreements

Compliance Agreements are written agreements between an entity engaged in growing, selling, processing, or moving regulated articles from a regulated area and the Ohio Department of Agriculture, setting forth specified conditions to prevent the spread of the gypsy moth. This agreement is needed by anyone moving regulated articles out of a regulated area to a non-regulated area and anyone in a non-regulated area receiving regulated articles from a regulated area.

One main requirement for the compliance agreement is that nurseries must apply a USDA-approved insecticide to the entire growing area in mid to late May. For more information, contact the Plant Pest Control Section at 614-728-6400 or your local nursery inspector.

Gypsy Moth Certificate

A Gypsy Moth Certificate specifically certifies a shipment for freedom from gypsy moth, allows the movement of regulated articles within the state.  They can be issued by a trained staff member of any entity holding a "Compliance Agreement" or by a State or Federal Inspector.

State PhytoSanitary Certificate

A State PhytoSanitary Certificate can be issued for individual loads of regulated articles being move out of state, but within the continental US. A "Federal PhytoSanitary Certificate" must be issued for any regulated articles being moved out of the United States to another country.  Both types of certificate can only be issued by either a State of Federal Inspector.


The image below shows an oak tree in Marion, Ohio affected by a heavy infestation of gypsy moth larvae (June 2018).
gypsy moth larvae on a tree
This image is of the same tree in Marion. Each egg mass can contain 500-100 eggs, so the population can quickly become out of control.
gypsy moth larvae on a tree
The same tree in Marion, completely defoliated by the infestation.
defoliated tree