Frequently Asked Questions

Gypsy Moth caterpillars feed on the leaves of many trees, especially oaks, and their populations can grow so quickly that they can strip all the leaves off of entire stands of trees, damaging them severely. When surveys indicate that that the population of the pest in an area is large enough to cause defoliation of trees in June, action is taken to reduce it at the request of landowners and communities whose counties are eligible and apply for treatment.Spray treatments reduce such outbreak populations below the level at which they can cause heavy defoliation.

Sites will receive a single aerial application of the microbial insecticide Foray [PDF, 113KB] , a brand name for Bacillus thuringiensis kurstaki [PDF, 66KB] (commonly called Btk). The active ingredient is a naturally occurring soil bacterium that kills Gypsy Moth caterpillars when they eat it.

Gypchek [PDF, 71KB] , a viral insecticide specific to Gypsy Moth caterpillars, will be applied where endangered or threatened moths or butterflies are present.

Both Btk and Gypchek are highly unlikely to cause any adverse health reactions. It is possible, but very unlikely, that people with severe food allergies or asthma may react to the spray.If you suffer from such conditions, the DNR suggests that you leave the area to minimize your risk of reactions. It is also advised that everyone in a spray area should take the simple precaution of staying indoors with the windows closed while the planes are spraying to avoid direct exposure.

The DNR makes spray block maps available on their website as soon as treatment areas are finalized. To find out if your property is in a spray block, look at the DNR's current treatment maps. Community governments may also have maps on their websites. Notices of spray locations also appeared in local newspapers.

Sprays are timed for when the caterpillars are in the first 2-3 weeks of development and leaves are expanded enough to intercept the spray. The timing is based on actual observations of caterpillars and leaf development. Spraying typically begins in mid-May in southern Wisconsin and early June in northern Wisconsin. Weather permitting, spraying may begin as early as 5:15 am and continue as long as weather conditions remain favorable. Please check the toll-free Gypsy Moth Information Line at 1-800-642-6684 (MOTH) by mid-May for daily updates. You can also sign up to receive updates via the DNR's email notification service.

Because the DNR Gypsy Moth Suppression Program is voluntary, anyone residing in a proposed spray block who does not want his or her property sprayed can opt out. Landowners who object must register their complaint by the local deadline with their county coordinator. Most county deadlines for registration of an objection are in mid-February. The objector's property and a buffer around it will be removed from the proposed spray block if they file before the deadline. Neighboring landowners whose property has been removed from the spray block to accommodate the objector are notified by the county coordinator.

• The goal of the DNR Suppression Program is to protect valuable trees from mortality by controlling gypsy moth population outbreaks in areas where the gypsy moth is established in quarantined counties.
• The DNR Suppression Program is offered as a voluntary partnership among counties, communities, landowners, and the state to suppress damaging populations of gypsy moth. Counties apply to participate in this program based on local concerns and motivation to treat specific areas.
• The DNR Suppression Program assists communities and landowners in the management of gypsy moth by providing the expertise and equipment for aerial sprays and applying to the Federal government for potential cost sharing. Treatments under this program are paid for by the communities and individuals being treated. If federal cost sharing is available, the state will pass these funds back to participating counties who may partially reimburse communities and individuals who paid for treatment.
• The goal of DATCP's Slow the Spread Program (STS) is to attack isolated, pioneering colonies of gypsy moth, west of the area where the pest is generally established in an effort to reduce the rate of this pest's expansion into new areas.
• DATCP's Slow the Spread Program determines spray areas based on gypsy moth population data collected in gypsy moth traps and surveys. This program does not work with landowners or local government to treat specific areas.
• DATCP's STS Program is not voluntary and is funded by the Federal Government to benefit an entire group of people and a large geographical area. Individual landowners whose land is sprayed as part of the STS Program may not receive any direct benefit.
• Both programs use naturally occurring soil bacteria, Bacillus thruingiensis var. kurstaki or B.t.k., applied by aerial spray.
• On sites with endangered species that would be affected by B.t.k., other gypsy moth specific treatments are used.
• To reduce expenses, both programs share the same aerial spray contractor.

If your county or community was sprayed in the past without formally applying to the Suppression Spray Program, you were sprayed as part of DATCP's Slow The Spread (STS) Program at that time. DATCP closely monitors gypsy moth populations west of Wisconsin's quarantined counties in the areas where gypsy moth is emerging in isolated, pioneering populations that they will spray to slow the spread of this pest westward. DATCP's STS Program does not take requests from landowners or municipalities for spraying or input on where spraying will take place.

Currently, if the DNR's Suppression Program is being offered to you, it means that gypsy moth populations are now at an outbreak level in your area. To get treatment assistance from the state, you must formally apply to the DNR's Suppression Program because DATCP will not be spraying in your area.

All of the tasks of a county coordinator are best done at the local level so that local concerns are adequately understood and addressed and local participation, ownership, and awareness are achieved. Each year many counties and municipalities are affected by gypsy moth in Wisconsin. The state depends on cooperators at the local and county levels to deliver the most effective, efficient, and understood suppression program possible.

• The county coordinator position is part-time with busy periods in September through November, and again in February through spray season in May or June.
• The DNR requires that the person filling this position be responsible to all landowners within the county they represent and that he or she is able to accomplish all local tasks by their deadlines.
• Any arrangement that can fulfill these requirements is acceptable. Counties may, for example, assign the work to a current employee, hire a part time employee, contract the work out, share a coordinator between counties, or enter into an agreement with a municipality to supply the coordinator.
• A participating county will usually designate the county coordinator by resolution or contract.
• Counties may add their administrative costs to the treatment cost when billing landowners or communities for the spray program. In this way, counties can set up a position that will be paid for as part of the cost of spraying.

Some of the duties of the county coordinator, established in ch. NR 47.913, Wis. Adm. Code are listed below. Although the responsibility for ensuring that these tasks are completed lies with the county coordinator, tasks may be delegated to the municipal level. County coordinators are responsible for meeting DNR dates in the timeline; they may implement earlier dates for municipalities to comply.

• Determine what properties within the county boundaries should be sprayed.
• Serve as the local, on-the-ground source of information and assistance for residents regarding the county's participation in the suppression spray
• Serve as the financial channel regarding the county's participation in the suppression spray
• Serve as the local, on-the-ground source of data to best time the spray treatment

The Suppression Program is a voluntary program that is administered through participating counties who have a county suppression program coordinator. To request that your property be included in a suppression spray, contact your county and municipal suppression program coordinators and provide them your address, township (if applicable), a brief description of your problem, and let them know that you want the spray and are willing to pay for it on your property.

If your county does not currently have a suppression program coordinator, contact your county clerk to register your concern. Clerks are not gypsy moth specialists and are not associated with the suppression program. However, residents typically bring their concerns to their county government through their county clerk.

You may also wish to contact your local municipal government to express interest in participating in the suppression program. Local interest is essential because this program is paid for by the people it serves, so many counties will not participate without municipal interest and involvement.

Note: Suppression Program sprays occur in May and early June of each year. The areas that will be sprayed are determined in September, October, and November of the previous year. Therefore, county and municipal suppression program coordinators and county and local government need to receive requests as early as possible. If you are experiencing a gypsy moth problem on your property this summer, report it right away if you would like to participate in the spray NEXT spring.