The California Department of Food and Agriculture has quarantined all of Los Angeles County for Asian citrus psyllid.
The designation, which covers 4,000 square miles, will restrict movement of citrus and other host plants, according to a news release.
The action comes after traps picked up several dozen Asian citrus psylla in the Echo Park area.
About a week earlier, the state quarantined all of Orange County after dozens of Asian citrus psylla were found in Santa Ana.
State ag officials say they hope the quarantines prevent the movement of the psyllid into the large citrus production regions in the San Joaquin Valley.
Asian citrus psylla can carry citrus greening, also known as huanglongbing of HLB. The bacterial disease is lethal to citrus trees but harmless to humans.
Once a tree is infected, there is no known cure. Yields and fruit quality decline, and the tree eventually dies.
So far, none of the psylla trapped in California have been infected with the greening bacteria, according to a news release.
To view a map of the quarantine area, visit http://www.cdfa.ca.gov.