The California Department of Food and Agriculture (CDFA) has established a quarantine of approximately five square miles in the Ojai area of Ventura County.

State and county inspectors are working closely with residents, growers, landscapers and related businesses in the area to monitor and contain an infestation of the European gypsy moth, a major pest of forests and landscape trees. Gypsy moth caterpillars feed on hundreds of kinds of plants and are capable of defoliating trees at an alarming rate.

“This quarantine is designed to contain the gypsy moth population in Ojai and to keep it from moving out of the area,” CDFA Secretary A.G. Kawamura said. “It is a necessary step so that we can eradicate this pest and protect our state from added quarantines and increased pesticide use over the long term.”

Four gypsy moths were trapped in Ojai in June 2007, triggering an intensive visual survey and heightened trapping that detected an additional seven moths this past summer, confirming that Ojai has an actively reproducing infestation. Additional visual surveys this fall revealed egg masses and larval cast skins on and near a property where a camping trailer had recently been parked after a trip that originated in the infested area of the northeastern U.S. Gypsy moths are known to deposit their egg masses on vehicles and outdoor equipment as well as on trees, buildings and other surfaces.

A single gypsy moth caterpillar can eat up to one square foot of leaves per day. In the northeastern United States, where this pest arrived from Europe in the late 1800s, millions of these caterpillars emerge each spring and devour large swaths of forest and foliage. When trees are repeatedly defoliated, they are rendered more susceptible to other pests and diseases, possibly leading to tree death and an increased potential for fire and erosion.

Young larvae feed primarily on oaks, aspen, birch, willows and alder, and older larvae feed on a broader range of trees including cedar, pine, spruce and fir. Common California species such as manzanita, western hemlock, Douglas fir and live oak are also prone to damage by this pest.

Inspectors have begun contacting residents and businesses in the quarantine area to notify them of the requirements and explain the specific rules for moving plants, yard waste, recreational vehicles and other objects that may harbor gypsy moth egg masses or other life stages of the insect. A map of the quarantine area is available online at www.cdfa.ca.gov/phpps/GypsyMoth.