Spongy Moth

Slow the Spread

Research Issue

The spongy moth (SM), Lymantria dispar (L.), has been gradually expanding its range in North America since its introduction into North America in 1869. USDA Cooperative Management Programs for SM fall into one of four categories: (1) a quarantine applied to areas with established populations to minimize the accidental movement of life-stages into new areas; (2) outbreak suppression in areas where SM is established; (3) eradication in areas where SM is not established; and (4) barrier-zone management, which is implemented in the transition zone between the uninfested and infested areas and is currently realized through the SM Slow-the-Spread (STS) program.

The STS program is a cooperative management program implemented by the US Forest Service Forest Health Protection in conjunction with state agencies from 10 US states. After several pilot programs that demonstrated the efficacy of a barrier zone program against the SM, STS was integrated into the USDA national strategy to manage SM in 2000. The premise of the STS program is to deploy a network of pheromone-baited traps across the leading population front, which extends from Minnesota to North Carolina. Within this trapping area, newly founded colonies that are detected are targeted for elimination in an effort to minimize their contribution to range expansion. Colonies are treated using primarily mating disruption tactics and to a lesser extent the biopesticides Btk and Gypchek. The STS program is evaluated by estimating yearly spread rates. Since 2000, the STS program has reduced SM spread by more than 60% compared to historical rates of spread. The reduction in spread is estimated to have prevented SM infestation and the impacts associated with outbreaks on more than 40 million hectares over this time. The partnership between the US Forest Service and participating states also promotes a well-coordinated, region-wide action based on biological need. The STS program yields a benefit to cost ratio of more than 4 to 1 by delaying the onset of the effects occurring as SM invades new areas.

Our Research

Although the STS program is a management program implemented by Forest Health Protection, Forest Service scientists in the Northern Research Station have been integral in developing the biological and technological basis for the program, and in the development and continual optimization of a computer-based decision algorithm used to prioritize treatments and evaluate the program. NRS scientists also coordinate a technical committee in support of the STS program, conduct research to address ongoing challenges, and meet regularly with state and federal partners.

Expected Outcomes

There is a continual need to address new challenges associated with the STS program. This includes incorporating enhanced strategies based on new developments in control tactics and geospatial technologies.

Research Results

As SM expands its range into new areas, there is often a need to develop regional-appropriate control strategies, and thus there is a need to better understand the population dynamics in these new areas. Research has highlighted these dynamics in new areas of invasions, and has led to the optimization of new control tactics.

Frank, K.L.; Tobin, P.C.; Thistle Jr., H.W.; Kalkstein, L.S. 2013. Interpretation of gypsy moth frontal advance using meteorology in a conditional algorithm. International Journal of Biometeorology 57: 459-473.

Tobin, P.C.; Bai, B.B.; Eggen, D.A.; Leonard, D.A. 2012. The ecology, geopolitics, and economics of managing the gypsy moth, Lymantria dispar (L.), in the United States. International Journal of Pest Management 58: 195-210.

Onufrieva, K.S.; Thorpe, K.W.; Hickman, A.D.; Tobin, P.C.; Leonard, D.S.; Roberts, E.A. 2010. Effects of SPLAT® GM sprayable pheromone formulation on gypsy moth mating success. Entomologia Experimentalis et Applicata 136: 109-115.

Tobin, P.C.; Blackburn, L.M. 2008. Long-distance dispersal of the gypsy moth (Lepidoptera: Lymantriidae) facilitated its initial invasion of Wisconsin. Environmental Entomology 37: 87-93.

Tobin, P.C.; Blackburn, L.M., eds. 2007. Slow the Spread: A National Program to Manage the Gypsy Moth. GTR-NRS-6. Newtown Square, PA:  USDA Forest Service, Northern Research Station.

Tobin, P.C., Sharov, A.A.; Liebhold, A. M.; Leonard, D.S.; Roberts, E.A.; Learn, E.R. 2004. Management of the gypsy moth through a decision algorithm under the Slow-the-Spread Project. American Entomologist 50: 200-209.

Sharov A.A.; Leonard D.; Liebhold A.M.; Roberts E.A.; Dickerson W. 2002. “Slow The Spread”: A national program to contain the gypsy moth. Journal of Forestry 100: 30-36.

Sharov, A.A.; Liebhold, A.M. 1998. Model of slowing the spread of the gypsy moth (Lepidoptera: Lymantriidae) with a barrier zone. Ecological Applications 8: 1170-1179.

Research Participants

Principal Investigators

  • Patrick Tobin, University of Washington, School of Environmental and Forest Sciences
  • Andrew Liebhold, USDA Forest Service Northern Research Station Research



Last Modified: March 4, 2022