With the discovery of Asian citrus psyllid in the heavily populated Los Angeles Basin, California's citrus industry and the University of California are asking for homeowners' help.
If they see something they suspect is the half-inch-long pest, they are asked to call the California Department of Food and Agriculture hotline at 9800) 491-1899, according to a news release.
The reason for the all-points-bulletin is Asian citrus psyllid can carry citrus greening, a disease lethal to citrus trees but harmless to humans.
In Florida, where greening is now endemic, it has cost the state's citrus industry millions of dollars in increased pest control, yield loss and tree replanting.
California citrus trees are entering the crucial period during the fall when they are flushing and have new growth. These tender shoots are prefered by the psyllid.
The mottled brown adults typically can be found on the inside of leaves, although they live anywhere on citrus trees and a few related ornamentals.
Nymphs congregate on the lighter green new flush.
Telltale symptoms include accumulate of honeydew, a sticky substance the pests excreete, on the leaves. Black sooty mold can frequently be found in conjunction with honeydew.
"If homeowners take a close look at the new growth on their citrus trees, if there is an Asian citrus psyllid infestation, they will be able to see signs with the naked eye," UC entomologist Beth Grafton-Cardwell said in the release. "But it's easier to see with a magnifying glass."
The Asian citrus psyllid was first found in the United States in Florida in the 1998. It has since been found in Texas, Louisiana, Georgia, Mississippi, South Carolina and now California. The pest also is found in Mexico.
In California, the pest was first identified in 2008 in portions of San Diego and Imperial counties.
Within the past few weeks, it's been confirmed in Orange and Los Angeles counties.
The potential for very rapid spread of citrus greening, also known as huanglongbing or HLB, isn't the only thing the California industry has learned from the Florida experience.
When trees started dying, Florida didn't have enough disease-free citrus stock available to replace them.
In California, all new trees are produced by nurseries with disease-free budwood from the UC Riverside Citrus Clonal Protection Program.
The program maintains a block of disease-free trees at the UC Lindcove Research and Extension Center in Exeter.
For decades, the parent trees were maintained in a field at Lindcove, but the increasing threat of citrus tristeza virus prompted UC to move true-to-type, disease-free trees into a screenhouse in the late 1990s.
Tristeza is spread by aphids.
The original screenhouse houses 500 potted and 100 in-ground trees representing 379 commercially important varieties. More than 200 of these citrus varieties are registered with the CDFA for budwood distribution.
The university is expanding the greenhouse to hold an additional 250 in-ground trees, says Georgios Vidalakis, director of UC Riverside Citrus Clonal Protection Program.