It starts with one, maybe a few, hitchhiking bugs.

They arrive attached to an exotic plant or in the moist bottom of a vase after crossing a border or an ocean or the sky.

Sometimes – maybe even most of the time – the invasive creature dies off soon after landing in Southern California. But a few find the region to their liking, thriving with no natural predators and abundant food. A few even gain such a powerful foothold in their new home that they become threats to crops and forests and industries.

John Kabashima of the UC Cooperative Extension walks through what is left of an oak tree infested with the goldspotted oak borer beetle that had to be chopped down and debarked in the Orange County forest last year. (File photo by Paul Rodriguez, Orange County Register/SCNG)

Tunnels created by the goldspotted oak borer beetle in the bark of an oak tree in the Orange County forest. (File photo by Paul Rodriguez, Orange County Register/SCNG)

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Metropolitan Water District of Southern California divers prepare to look for the tiny quagga mussel in 2007, near the intake tower of Diamond Valley Lake near Hemet, Calif. Water officials are hunting down an invasive mussel that has been spotted in California for the first time and threatens to choke water supplies. ( Ramon Mena Owens, The Press-Enterprise/SCNG)

A sycamore tree shows signs of Polyphagous Shot Hole Borer (PSHB) at Crystal Springs picnic area in Los Angeles. (File photo by Ed Crisostomo, Orange County Register/SCNG)

A native beetle larvae found in a dead oak tree branch. The native beetles add to the stress created by the drought and the non-native, invasive goldspotted oak borer beetle. (File photo by Paul Rodriguez, Orange County Register/SCNG)



Quagga and zebra mussels can grow on hard surfaces, attaching themselves to boat propellers, hulls and intakes where they can be transferred to another body of water. (Photo courtesy of the National Parks Service)

John Kabashima of the UC Cooperative Extension chips away at the bark of an oak tree looking for tunnels created by an infestation of the goldspotted oak borer beetle in the local Orange County forest last year. (Photo by Paul Rodriguez, Orange County Register/SCNG)

The quagga mussel has been found in local lakes. (Photo courtesy of California Department of Fish and Game)

And as our climate changes, the problem is only accelerating.

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Before 1989, California tracked about six new invasive insects a year, a species count that doesn’t include mammals, fish and other creatures. Between 1989 and 2010, the invasive species count in the state jumped by about 50 percent, to roughly nine newcomers a year, according to experts.

“It’s sort of a recipe for disaster – or success – depending on your point of view,” said Mark Hoddle, an entomologist and biological control specialist who studies invasive species at UC Riverside.

With the state Dept. of Fish and Wildlife declaring June 2-11 Invasive Species Awareness Week, Hoddle and other experts pointed to three invasive species that have become particularly problematic in Southern California.

The Asian citrus psyllid, Hoddle said, poses a potentially existential threat to California’s $3 billion citrus industry.

The tiny sap-eating bug thrives on citrus trees, transmitting a bacteria that makes the tree’s leaves wither and its fruit bitter, dry and misshapen – or nonexistent.

“This has been a catastrophe in Florida,” Hoddle said of the psyllid.

“Some experts predict that in 10 years Florida may not have a commercial citrus industry. We are right at the beginning of this possible outcome in California.”

Another problem invader, which first became common in the Cleveland National Forest, is the gold-spotted oak borer, a tiny, bullet-shaped beetle that has downed tens of thousands of trees. People assist the beetle’s expansion by cutting the fallen trees for firewood and transporting it to new forests.

The loss of trees results in lost habitat for animals. Waterways once shaded by trees become warmer and drive away animals. The borer is now believed to be in several forest lands throughout California.

“These things become very interconnected and form these feedback loops,” Hoddle said. “You can see how this stuff fosters more and more problems.”

Another invader, one that’s threatening the state’s water infrastructure, is the quagga mussel.

It’s believed the mussel originally made its way to North America in the 1970s in the ballast water of Eastern European ships that docked in the Great Lakes, where it gained a foothold. In 2007, the quagga was detected in the Colorado River, apparently after hitching a ride on the bottom of a boat or a piece of equipment that was used in Lake Mead.

The quagga mussel constantly reproduces, building layers that have to be scraped off water infrastructure and can survive long voyages out of water by sealing itself up in its shell. The Metropolitan Water District – Southern California’s main water importer – has spent $30 million just on chlorine (which can kill the quagga) in the 10 years since the mussel made it into California waterways, said Bob Muir, a spokesman for the agency.

“They clog up and colonize infrastructure in multiple layers of mussels which can impede the flow of water,” said Martha Volkoff, the environmental manager in the invasive species program of the Department of Fish and Wildlife. “As the break off they decompose and alter water quality.”

There are signs that the quagga recently spread into the Santa Ana pipeline that sends water from Silverwood Lake in San Bernardino to Lake Perris in Riverside. In February, the Department of Water Resources reported that larvae from a zebra or quagga mussel were detected in the pipeline, though state officials are still awaiting genetic tests to determine which type of mollusk it is.

Because of the proliferation of invasive species and limited resources to control them, Hoddle said it will become a matter of picking battles.

“We can’t fight every problem,” he said. “We have to prioritize.”

Hoddle and others describe the fight as a game of whack-a-mole, if the mole came from Poland or Thailand or Australia.

“Los Angeles International Airport gets 50 million visitors a year. Can you possibly check everybody’s suitcase?” Hoddle said.

“You think of all the boats coming into Long Beach, the traffic coming in through the California border system. The pressure is unrelenting. Every day, there’s stuff coming in.”