Six Asian citrus psyllids have been found in three traps south of the city of Porterville in the heart of California's main citrus-producing region.
The finds come only about three weeks after Tulare County agricultural officials eliminated restrictions prompted by three earlier finds.
California Department of Food and Agriculture inspectors have begun hanging additional traps to determine the extent of the infestation, according to a news release.
The state and the U.S. Department of Agriculture Animal and Plant Health Inspection Service will work together to determine the next steps.
The concern is that Asian citrus psyllids can carry huanglongbing, also known as HLB or citrus greening.
The bacterial disease can devastate citrus trees but it harmless to humans or animals.
Citrus greening is widespread in Florida but has only been found on one residential property in California, and that was in the Hacienda Heights neighborhood of Los Angeles.
View the map of psyllid finds by visiting the Tulare County Agriculture Commissioner's website.
To report possible Asian citrus psyllids in California, contact the CDFA pest hotline at 800-491-1899.