PEPC and Parkplanning may experience intermittent outages from 8 PM MT to 12 AM MT on June 18th due to network maintenance.

Wisconsin Cooperative Spongy Moth Program Slow-The-Spread

Saint Croix National Scenic Riverway » Wisconsin Cooperative Spongy Moth Program Slow-The-Spread » Document List

The US Forest Service, State & Private Forestry (Forest Service, S&PF), in partnership with the state of Wisconsin's Department of Agriculture, Trade and Consumer Protection (DATCP) is planning to conduct aerial treatment of a pheromone mating disruption product targeted at Lymantria dispar (formerly gypsy moth, now spongy moth) throughout the state of Wisconsin. This treatment is part of the national L. dispar Slow-the-Spread (STS) program which has been ongoing since 1990. One of their proposed sites overlaps our park boundary near Hayward, WI.

The STS program is a cooperative integrated pest management project conducted between the US Department of Agriculture and state agencies with the goal of slowing the spread of spongy moth (SM) by 60% of its historical spread rate. Each year the Forest Service, S&PF works with the 10 participating states to pinpoint areas along the leading edge of the SM invasion wave to conduct aerial treatments in "potential problem areas" where populations of SM are seen to be expanding.

In spring 2022, an EA was completed by Forest Service, S&PF and DATCP to treat outlier SM populations in Wisconsin with either the bacterial insecticide Btk or mating disruption treatments along an area referred to as the Action Zone. Treatments are proposed on fifty-seven (57) sites in seventeen (17) counties totaling approximately 163,491 acres in 2022. The EA Action Zone encompasses approximately 1,073 acres of NPS lands which are proposed for treatment with mating disruption (mid-summer). The NPS acres are all within the Sawyer11 treatment block of the Action Zone along the Saint Croix National Scenic Riverway located in Sawyer County. Sawyer County is not a designated quarantine area for SM. The presence of SM within park boundaries in this location is likely although exact locations have not been documented by the park. NPS acknowledges the negative impacts to vegetation from SM in the surrounding landscape and approve of the use of this proactive management technique within park boundaries. While Forest Service, S&PF, DATCP, and NPS will share the same EA, the NPS will issue a separate decision document for treatments that overlap NPS owned and managed lands.

The active ingredient in the mating disruption product is racemic disparlure, the sex pheromone for SM. Mating disruption is not an insecticide. The goal of this type of treatment for SM is to permeate the air with disparlure, which in areas of low population density has been shown successful in preventing males from locating and mating with the flightless females. The product being used for mating disruption is known as SPLAT (Specialized Pheromone & Lure Application Technology). This product is essentially a mixture of water, vegetable oil, and a biodegradable wax which serves as a carrier for the pheromone. This type of product is most successful when applied a few weeks prior to male moth emergence and is applied aerially using fixed wing aircraft. This period typically takes place in mid to late June in Wisconsin. The NPS owned and managed lands within this treatment block will be treated with a single mating disruption application in early to mid-July, prior to the flight period of male SM. The mating disruption is applied at a rate of 15g active ingredient per acre and is applied once per treatment site. 

Contact Information

Caitlin Nagorka
715-501-0011