Lymantria dispar in the United States
In 1923 attempts were made to prevent the westward spread of the moth by maintaining a barrier zone extending from Canada to Long Island of nearly 27,300 km2.
Small, isolated infestations have sporadically occurred in Utah, Oregon, Washington,[3] California, and British Columbia, but efforts have been taken to eradicate them.
In wooded suburban areas, during periods of infestation, gypsy moth larvae crawl over man-made obstacles and sometimes enter homes.
[5] Gypsy moth populations usually remain low, but occasional increases to very high levels can result in partial or total defoliation of host trees.
In the eastern US, the gypsy moth prefers oaks, aspen, apple, sweetgum, speckled alder, basswood, gray and paper birch, poplar, willow, and hawthorns, amongst other species.
The gypsy moth avoids ash trees, tulip-tree, cucumber tree, American sycamore, butternut, black walnut, catalpa, flowering dogwood, balsam fir, cedar, American holly, and mountain laurel and rhododendron shrubs, but will feed on these in late instars when densities are extremely high.
[9] In coastal Maine and Cape Cod, Massachusetts, caterpillar-triggered rash is much more likely due to exposure to the browntail moth (Euproctis chrysorrhoea).
Although not preferred by the larvae, pines and hemlocks are subject to heavy defoliation during gypsy moth outbreaks and are more likely to be killed than hardwoods.
A complete defoliation can kill approximately half of pine species and 90 percent of mature hemlocks because conifers do not store energy in their roots; an exception is larch.
Small mammals are the largest predators in low density gypsy moth populations and are apparently critical in preventing outbreaks.
Calosoma (ground beetles of European origin), cuckoos, and flocking birds such as starling, grackles, and red-winged blackbirds, are attracted to infested areas in high gypsy moth population years.
To concentrate the caterpillars, a strip of dark cloth about 12 inches wide – for example, burlap or old blue jeans, is tied around the tree at eye height.
The gypsy moth currently occupies less than a third of its potential range in North America and considerable resources are directed at minimizing its expansion into these areas.
When captures are positive for several consecutive years, this indicates that a population is establishing and these are eradicated, usually via the application of the bacterial pesticide Bacillus thuringiensis ('Bt').
[8] In 2008 California agriculture officials quarantined a rural 5-square-mile (13 km2) section of Ventura County near Ojai to prevent the spread of a newly found gypsy moth colony.
[13] The decision to use pesticides is influenced by a number of factors, such as the quantity of visible egg masses, The percentage of preferred hosts, presence of dead or dying branches, and proximity to heavily infested woodlands.
[8] The most commonly used chemical pesticides currently registered by the US Environmental Protection Agency (EPA) for use against the gypsy moth contain carbaryl, diflubenzuron, or acephate.
Several studies by Peter G. Kevan et al of the University of Guelph conducted between 1975 and 1995 showed serious reduction in pollination of blueberry and other crops due to aerial applications of insecticides that killed non-target wild bees.
Mating disruption has been successfully and safely used to manage gypsy moth in a number of eastern US states stretching from Wisconsin to North Carolina under the federal Slow the Spread (STS) program.
SPLAT GM is also packaged and sold in handheld dispensers for manual application to smaller areas of 2.5 acres or more, and can be used as an alternative or complement to other gypsy moth control solutions.
