USDA Forest Service

Gypsy Moth In North America


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Gypsy Moth Spread in North America

The gypsy moth is native to Eurasia and was introduced to North America in 1868 or 1869 by E. Leopold Trouvelot near Boston, Massachusetts. Since then, its range has been slowly spreading.





The current gypsy moth range in North America (shown in red) includes all of the northeastern US and portions of the southeast and midwest, as well as portions of eastern Canada. It's distribution in Michigan and parts of Ontario is the result of an accidental introduction to Michigan in the early 1960's and a failure of attempts to eradicate this population.

The historical rate of spread has been estimated as:

Spread Rate
Period             km/yr
1900-1915            9.5
1916-1965            2.8
1966-1989           20.9
(from Liebhold et al. 1992. J. Biog. 19:513-520)

The gypsy moth is currently spreading at a rate of about 21 km / year along its border to the west and south. Since females are not capable of flight, this spread can be attributed to natural movement of wind-borne 1st instar larvae and accidental movement of life stages by humans. We believe that accidental movements of life stages found new isolated populations just ahead of the expanding front and these coalesce over time. More detailed information about gypsy moth spread can be found here. Click here to see some recent work on estimation of the the expanding front.
(map courtesy Virginia Tech Univ.)
The USDA Forest Service is currently beginning a national project to slow the spread of the gypsy moth. This project is based upon the use of grids of pheromone traps along the expanding front to detect isolated colonies. These colonies are eradicated or suppressed in order to prevent them from coalescing and this decreases the rate of spread. Click here to find out more about this project from this server or click here to visit the national STS homepage.
(map courtesy Virginia Tech Univ.)

  • Click here to see more maps of historical gypsy moth spread.
  • Click here , to see the results of annual gypsy moth surveys for detecting new isolated infestations.

Return to Gypsy Moth in NA

Last modified 10-29-03 by Sandy Liebhold .

USDA Forest Service - Northeastern Research Station

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