Gypsy Moths in the U.S.

How did it get here?

E.L. Trouvelot, who was interested in breeding a better silkworm, first brought the gypsy moth from France to Massachusetts in 1869. Some moths escaped to his neighborhood and quickly became established. Since their introduction, gypsy moths have spread north, south, and west, eating their way from Maine to North Carolina and into central Wisconsin. Despite state and local control efforts, the infestation continues to spread south and west and threatens to move into Minnesota.

USDA Forest Service: Gypsy moth in north america

There are three broad stages of population development for a nonnative invasive species such as the gypsy moth.

  • Pre- or uninfested stage when the pest is rarely found
  • Generally infested stage, once the pest has become permanently established in an area
  • Transition stage in between, when the pest becomes established and populations begin to build.

 Diagram: Gypsy Moth Spread

Diagram showing gypsy moth spread pattern


When gypsy moths become permanently established within a county, the county is quarantined. Quarantines do not ban the movement of goods from one area to another, but they do regulate how items can be moved. Within a quarantined area, commercial export facilities will need a compliance agreement with USDA-APHIS in order to legally ship their products. At this time (June 2006) there are no quarantines in Minnesota.

USDA APHIS: Gypsy moth quarantine area

Questions about Minnesota quarantines? Contact the "Arrest the Pest" at [email protected] or 888-545-6684.


What programs are there to help?

The management strategy varies for each population stage, as does the financial support available for state programs and the lead agency within the state responsible for pest management.

 Pre-infestationTransitionGeneral Infestation
Population characteristicsMoths are not present or are rare. Isolated infestations may occur as a result of accidental introductions.Moths are present but difficult to find. Low-density populations occur in distinct islands of infestation that are not yet widespread.Moths are present in increasingly large numbers and infestations are more or less contiguous throughout the area.
Primary management strategyDetect and eradicate small isolated infestation in front of general infestation.Monitor pest numbers and treat population peaks to slow the spread of infestationMonitor forest damage and treat high-value forest lands where needed to limit potential losses. 
Federal supportUSDA Animal and Plant Health Inspection Service provides direct technical and financial assistance.USDA Forest Service research provides technical support. Financial assistance is provided the National Slow the spread (STS) Foundation.USDA Forest Service, State and Private Forestry, provides technical and financial assistance.
Survey methods"Delta" traps (small triangular cardboard tents) are baited to attract male moths."Milk-carton" traps (cardboard boxes shaped like milk cartons) are baited to attract male moths.Egg mass surveys and aerial surveys are used to map.
Most common treatmentsBtk or GypchkDisrupt II or BtkBtk
Lead state agencyMinnesota Department of AgricultureMinnesota Department of AgricultureMinnesota DNR

USDA-APHIS Gypsy moth programs

Slow The Spread Program