The discovery in Santa Ana, Calif., of a tiny insect that typically carries a tree-killing disease has brought California's $1.6 billion citrus industry one step closer to an agricultural disaster, experts said.

State agricultural officials said last week that they recently trapped five adult Asian citrus psyllids on a lemon tree at a home in Santa Ana, in Orange County. They have sent the insects off to a lab to see whether they carry the bacteria that causes citrus greening, a disease that has ravaged groves in Florida and wiped out much of the citrus industries in China, India, Saudi Arabia, Egypt and Brazil.

Until now, the bugs had been found south of Orange County in San Diego and Imperial counties, but the nearest outbreaks of citrus greening are in Louisiana and Mexico's Yucatan Peninsula. Test results are expected later this week or next week.

"Wherever the psyllid goes, the disease has followed. ... Our only hope is to find the disease early and try to deal with it," said Ted Batkin, president of the Citrus Research Board in Visalia, Calif.

"Having it as far north as Santa Ana means that the pest could be anywhere in the entire Los Angeles basin. This is not good. We are not containing the pest," Batkin said.

Other experts also believe there is little chance that state and federal efforts to prevent the disease from reaching California will be successful.

"It is just a matter of time," said Beth Grafton-Cardwell, a University of California, Riverside, entomologist based in Central California's San Joaquin Valley. "Beating down the number of psyllids will help slow it, but not stop it."

The bacterial disease, also called Huanglongbing, or HLB, ruins the taste of fruit and juice before killing the plants, experts said, and there is no known cure or method for ridding a region of the pathogen once it has struck. It's transmitted to healthy trees by the psyllid after it feeds on infected trees. It does not afflict humans.

Batkin said the industry — and people who have orange and lemon trees in their yards — are in a race against time. He's hoping containment efforts will hold down the bug population and find any diseased trees to reduce damage from citrus greening until researchers devise a cure or develop disease-resistant plants.

"We need to find and remove any trees that may have been infected so that the psyllids can't use them as a reservoir to pick up the disease and spread it around the state like they did in Florida," Batkin said.

Most experts believe the first spotting of the disease will be on a backyard tree rather than a commercial orange grove, which are regularly inspected by growers. That's why they are urging homeowners to learn what to look for at www.califor niacitrusthreat.org or by calling the California Department of Food and Agriculture hot line at 800-491-1899.

Including state, industry and federal efforts, about $50 million is earmarked for citrus greening research and containment efforts, officials estimate. Much of the research focuses on developing a disease-resistant tree.

But until there are breakthroughs, California's strategy is to hold down the number of psyllid colonies that settle in California, and then find and root out any infected trees quickly. This is a problem because the disease can lay dormant for years before a tree shows symptoms.

The task is made even more complicated by the recent discovery of six infected citrus trees on Mexico's Yucatan Peninsula.

They could eventually connect with colonies in California and spread the disease throughout the state, said Grafton-Cardwell, who calls citrus greening, a "grower's worst nightmare."

The discovery of the psyllids in Santa Ana comes just a year after the insects jumped over the border from Mexico and established colonies first in San Diego County and later in Imperial County.

Despite the discovery of the bug, California has so far escaped the feared citrus greening disease. That's because the psyllids that have established colonies in Southern California have yet to come in contact with the disease that causes the trees to die.

What inspectors fear is the Florida scenario, in which the combination of a few infected trees and a large population of psyllids overwhelmed the state.