The county Department of Agriculture's plant-sniffing dog was standing on a conveyor belt at a San Diego FedEx distribution center when Friday's 6:50 a.m. sort began. She rushed up to meet the oncoming boxes, bounding over and between them, snout down, looking for signs of life.

Dog handler Jeremy Partch and his 4-year-old Labrador retriever, Friday, work conveyor belts at county shipping centers in San Diego and North County five days a week, looking for plant and animal material that might be carrying crop-killing insects from out of town.

The team is at the front lines of the county's uphill battle to protect its $1.5 billion agricultural industry from non-native insects, untold numbers of which could cause catastrophic damage to crops and cost taxpayers millions of dollars to eradicate.

"So far, we've found four (species of ) pests entering the state," Partch said. "If any of those got established ---- I mean, that's justification (for the dog program's cost) in and of itself."

State and county agriculture experts have noted a year-over-year rise in the number of invasive insects spotted here, and many think shipments of plants and produce between people is one of the biggest reasons.

Catching insects before they reach their destinations in San Diego can prevent infestations of pests like the Mediterranean fruit fly, found recently in Escondido, officials said. An uncontrolled Medfly infestation could cost California's statewide economy an estimated $1.9 billion in lost crops and jobs, increased pesticide use and trade restrictions.

The dog team joined the county's surveillance program for incoming plant shipments at parcel facilities such as FedEx and UPS in December 2008, according to a department report. The $1.5 million statewide program was funded in the 2009-10 fiscal year with money from the Farm Bill and federal appropriations.

There are five dog teams in California, covering Fresno County, the Sacramento Valley, the Inland Empire, the San Francisco Bay Area and San Diego County.

San Diego expects to have a second dog team working by the end of the year, county Agriculture Commissioner Bob Atkins said in September.

Shipping facilities are scattered around the county and sorts commonly begin before 7 a.m., so the team can usually visit only one facility each day, Partch said.

The rest of his days are spent completing paperwork and calling senders of problematic plants ---- sometimes repeatedly ---- to tell them what happened and explain how to comply with shipping rules in the future, he said.

Friday seems to enjoy her part of the work, especially the treats that follow a correct identification or "hit", Partch said. She scratches a box with her front paws to signal suspect contents.

The team sees a lot of cut flowers during sorts, Partch said. Friday hits so many boxes from the floral company ProFlowers, team members joke that she can read.

Ann Sixtus, a senior agriculture inspector at the department, was the box checker on duty with Partch on Friday. Her job was to open the hit boxes, and check the contents for bugs and labeling violations.

If the contents had been labeled correctly and are found free of insects or other code violations, they are repacked, receive a "Passed California Agriculture" sticker, and are placed back on the belt for distribution.

If inspectors find an insect, the boxes are hastily closed, sealed with tape and sent off to the lab, Sixtus said. Inspectors confiscate boxes with contents or labeling in violation of state or county codes.

Besides flowers, Friday has found snakes, rats and plants, including marijuana and psychedelic mushrooms.

"If it's alive, she'll hit it," Partch said. "She won't hit a box of dead seafood, but she'll hit a box of living goldfish swimming around in bags of water. I don't know how she does it."

On Friday, Sixtus opened a box hit by the dog that had a biohazard symbol on it. Inside were vials of what appeared to be blood packed with dry ice.

The team opened and inspected 16 packages that were indicated by the dog at the sort, and none of them were illegally shipped or wrongly labeled, Partch said with satisfaction.

"Our numbers are going to plateau out, but that's just because we're getting a lot more compliance," he said. "I like to catch the bad bugs and everything, but I really like to see compliance. It means we're making a difference."

Contact staff writer Morgan Cook at 760-740-3516.