Gypsy Moth in North America

 

 

Gypsy Moth In North 

America

 

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Res. Work Unit NE-4557

Morgantown 

180 Canfield ST. 

Morgantown, WV 26505

(304) 285-1503 

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Gypsy Moth Management

Because the gypsy moth has many 

undesirable effects on trees and 

forests, efforts are made to manage 

the problem. Eradication and Slow 

the Spread are methods used to 

prevent or postpone the 

establishment of gypsy moth 

populations in portions of the 

country where it currently does not 

exist. Suppression, silviculture, and 

biological control are methods used 

to manage established gypsy moth 

populations. 

Eradication

In states that currently do not have established gypsy moth populations 

(e.g. California, Kentucky, Minnesota) grids of pheromone traps are used 

to detect new, isolated populations. These populations are usually the 

result of the accidental introduction of gypsy moth life stages on articles 

such as recreational equipment, fire wood, or nursery material. 

Pheromone traps are very sensitive methods for detecting gypsy moth 

populations, even when they exist at such low densities that egg masses 

or caterpillars may not be found. When males are trapped for several 

years at the same location, this is evidence of a reproducing population. 

In these cases, an effort is usually made by state and federal agencies to 

eradicate (totally eliminate) this infestation. Eradication methods vary, 

but sometimes include spraying with chemical or biological pesticides, 

mating disruption, or mass-trapping. 

Slow the Spread

Gypsy moth populations in N. America are slowly expanding their range. 

Because, it may take many years before the gypsy moth range spreads 

to include all of N. America, there is logic in attempting to slow the rate 

of spread into uninfested areas. Doing so will reduce gypsy moth impacts 

in those areas. Currently, the USDA Forest Service is undertaking a 

major effort to slow gypsy moth spread. Scientists believe that it is 

impossible to stop gypsy moth spread but evidence to date indicates that 

it is possible to reduce the rate of spread by 50% or more. This is 

accomplished by using grids of pheromone traps along the expanding 

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Gypsy Moth in North America

front to detect isolated colonies. These colonies are then suppressed or 

eradicated using environmentally benign methods. More information 

about this method can be found at the Slow the Spread Project 

homepage. 

Suppression

Most of the negative impacts associated with the gypsy moth occur at 

high densities. Therefore, a common approach to gypsy moth 

populations is the direct suppression of populations in order to minimize 

these effects. These efforts are sometimes carried out by individual 

homeowners using ground applications of pesticides to individual trees, 

aerial application of pesticides by private contractors, or aerial 

applications of pesticides in cooperative state/federal programs. 

Materials used in these treatments include the chemical pesticide 

"Dimilin", or the biological pesticides, Bacillus thuriengensis and 

"Gypchek", a formulation of the naturally occurring gypsy moth virus. 

Information about these programs can be obtained by contacint your 

local county extension agent. Information can also be obtained from 

USDA Forest Service Forest Health Protection group. 

Biological Control

The gypsy moth has a variety of natural enemies (predators, parasites, 

and diseases) that naturally control populations. Research scientists are 

still searching for natural enemies in the native range of the gypsy moth 

that might be introduced to N. America for control purposes. Some effort 

is also underway to develop methods to increase the effectiveness of 

natural enemies that are already established. 

Silviculture

The gypsy moth can have substantial effects on the growth and survival 

of forest trees. One approach to managing this problem is to use 

silvicultural methods to reduce the susceptibiltiy (defoliation potential) 

and vulnerability (tree mortality) of forests to the gypsy moth. This can 

be accomplished by selectively cutting host trees preferred by the gypsy 

moth and/or cutting trees that are in poor condition and likely to die 

following defoliation. More information on silviculture can be found at the 

Gypsy Moth Silvicultural Experiment Tour

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Last modified 10-29-03 by Sandy Liebhold 

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USDA Forest Service - Northeastern Research Station 

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