Skip to main content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Forest Health News 2019

Effectively slowing the rate of spread of the exotic Lymantria dispar

By Tom Coleman, USDA Forest Service


September 2019

Lymantria dispar caterpillar

Lymantria dispar dispar caterpillar. Photo by: Tom Coleman.

Since 2000, the National Gypsy Moth Slow the Spread (STS) Program has effectively slowed the rate of spread of the exotic Lymantria dispar dispar in the eastern U.S. STS represents one of several management strategies under the USDA’s National Gypsy Moth Management Program. STS is a collaborative effort between the USDA Forest Service, Forest Health Protection, USDA Animal and Plant Health Inspection Service, 11 state agencies, a non-profit foundation, and two universities. Together these groups annually monitor >62,000 pheromone traps and suppress new Lymantria dispar populations on >300,000 acres of private, state, and federal land along its expanding invasion front.

Aerial application being conducted for STS

Aerial application being applied to slow the spread of Lymantria dispar dispar. Photo by: Tom Coleman.

For more information about Lymantria dispar in the U.S., its management, and the STS program, visit the Natioinal Gypsy Moth Slow the Spread Program story map.