EAU CLAIRE — Due to diminishing need for the program, the Wisconsin Department of Natural Resources is looking at closing its gypsy moth suppression program, DNR Invasive Forest Insects Program Coordinator Andrea Diss-Torrance said during a public hearing Dec. 19 at DNR service centers in Eau Claire, Fitchburg, Milwaukee and Green Bay.
“This is a service currently that is small enough that it is manageable on a local level and can be serviced by the private industry,” Diss-Torrance said. “The state can, at this point, step back and really should step back so that we’re not in competition with businesses that could provide these services.”
The DNR has offered a state-run suppression program since 2000 to deal with areas with established gypsy moth populations going through their typical boom-bust population density cycles, Diss-Torrance said.
“When the gypsy moth is in outbreak, it can rise to very high densities and cause nuisance and defoliation of trees,” she said. “In 2000, we were going through the first build-ups of populations that were threatening to defoliate urban areas and some rural forests. The state stepped up to provide this service partially because aerial suppression of forest pests was a very rare occurrence. There really wasn’t any existing structure to help communities or individuals set up an aerial spray that would be necessary for when you have more than 20 acres of an area threatened with defoliation.”
The invasive gypsy moth defoliates trees during its caterpillar stage. The DNR gypsy moth suppression program is one of two state programs intended to keep gypsy moth numbers in check. In recent years, the program has controlled gypsy moth infestations throughout the eastern two-thirds of Wisconsin where gypsy moths already exist.
According to Diss-Torrance, in 2004 the DNR sprayed about 50,000 acres in eastern Wisconsin to control gypsy moth populations. Since then demand for suppression spraying has decreased and in 2017, the DNR’s suppression program treated just 188 privately owned acres in south-central Wisconsin.
“That’s really quite small for a state spray program,” Diss-Torrance said. “Pennsylvania does hundreds of thousands of acres on occasion.”
Diss-Torrance said that in other states with gypsy moth populations, private contractors have started providing spraying services to control outbreaks, and she expects the same to happen in Wisconsin.
“It’s certainly something that could be done by a smaller contractor, a smaller program than a statewide program, something more local,” she said. “We did expect to close this program after 10 to 15 years.
“Typically, when gypsy moth comes into an area, the first outbreak is quite severe, but then it moderates over time and outbreaks become less damaging as natural enemies become established and the forest is no longer naive. We expected that the demand for large spray projects would decrease and become more manageable for smaller contractors.”
Diss-Torrance also said that on several occasions during years the DNR had expected a booming gypsy moth population, the severity of outbreaks was limited by biological controls like Entomophoga maimaiga, a fungus introduced in the late 1990s that benefited from wet springs preceding the projected population booms.
“In 2004, Entomophoga maimaiga ... came in and really hammered the population,” Diss-Torrance said. “It took the population down so quickly that we had only 20 acres of defoliation that year, even though we were expecting heavy populations and heavy defoliation across the entire eastern side of the state.
“That was really gratifying. We were happy to see that our biological control worked extremely well.”
The Wisconsin Department of Agriculture Trade and Consumer Protection will continue its separate initiative to delay the introduction and spread of the insect into new areas in the western third of the state. This “Slow the Spread” initiative will continue to use aerial spraying methods to slow down the movement of gypsy moths into new territory.
The gypsy moth is a non-native pest that is well-established in the eastern two-thirds of Wisconsin. The Wisconsin DATCP focuses its efforts on the western edge of that area in an attempt to slow the spread of this destructive insect.
Gypsy moth caterpillars feed on the leaves of about 300 species of trees and shrubs. At high populations, they may completely defoliate trees in the spring. Repeated defoliations may weaken trees and leave them susceptible to other insects and diseases. Adult gypsy moths do not feed, but the adult females lay thousands of eggs, which are easily transported to new areas by humans on firewood, outdoor furniture, camping equipment and vehicles.
Fifty of Wisconsin’s 72 counties are under quarantine for gypsy moth. The DATCP does treat in the counties just west of the quarantined counties and on the western edge of some of the quarantined counties as part of the Slow the Spread program, a cooperative effort with the U.S. Department of Agriculture’s Forest Service and 10 states.
The public comment period ended Dec. 19, and Diss-Torrance then summarized comments to include in a package that will go to the Natural Resources Board requesting their adoption of the proposal to deactivate the suppression program at their meeting Jan 23-24. If the proposal is adopted, it would then go to the Legislature and the governor for their approval. Diss-Torrance said she expects the rule change to go into effect by mid-summer.
Diss-Torrance said counties usually submit applications to the program during the first week of December. Dane County has requested eight areas be sprayed next year, and the application for treatment and cost sharing is already in processing, she said.
“We will complete the spray project planned for this spring 2018,” she said. “Once deactivated, the program will not accept applications. Deactivating the program in mid-summer will be a clean closure.”
Diss-Torrance said the DNR will re-evaluate the program in several years to decide if the program needs to be reactivated or can be closed permanently.
“We would only recommend that it be reactivated in the event of a catastrophic regional outbreak where the demand would exceed the ability of the private sector to meet the need,” she said.
Information on managing gypsy moth infestations is available through Wisconsin’s Cooperative Gypsy Moth website, gypsymoth.wi.gov.