Australian Beetle Spreads in Its Attack on Eucalyptus

<p>A deadly borer beetle from Australia, threatening millions of Southern California eucalyptus trees, has spread from the San Fernando Valley into the Santa Clarita Valley and Ventura County within the last two months, a forestry official said Wednesday.

The brownish-black pest, called the eucalyptus longhorn borer (Phorancantha semipunctata) , was spotted in Ventura County in late October, more than 100 miles from where it was first sighted three years ago, said Joe Ferrara, head deputy forester for the Los Angeles County Forestry Division.

If not controlled, the borer will eventually spread throughout the state, wiping out millions of eucalyptus trees in the process, he said.

“I consider them a major danger,” Ferrara said. “I wouldn’t have said that eight months ago.”

Non-Native Tree

Eucalyptus trees, the borer’s main food source, are the most widely planted non-native trees in California. Because of their ornamental qualities and tolerance to Southern California’s dry, Mediterranean climate, Ferrara said, they are commonly planted in new housing developments, such as those in the Santa Clarita Valley, and are used for freeway and roadside landscaping and as windbreaks.

The beetle feeds on stressed and cut eucalyptus trees by burrowing under the bark and eating the wood. Healthy eucalyptus trees produce sap that kills the insect, Ferrara said. But the insect is drawn to trees in stress from several dry years and dead wood, such as that stored by homeowners to burn in their fireplaces.

In the burrowing process, the insect makes tunnels that may be more than an inch wide and several feet long beneath the bark, Ferrara said. Ultimately, the pest’s tunnel surrounds the tree, prevents it from receiving nourishment and kills it.

The borer was first found in California near El Toro in Orange County in October, 1984. Since then, it has spread into Los Angeles, Ventura, San Bernardino, Riverside and San Diego counties, he said.

Los Angeles County officials first noticed the insect early last year in several San Gabriel Valley parks. Later that year, it spread to the San Fernando Valley.

Ferrara said he would not be surprised if the insect is sighted in Santa Barbara County soon.

Shipment of Goods

The longhorn borer is believed to have been brought to California with a shipment of goods from Australia, Ferrara said.

“Since its entrance, it has spread rapidly,” he said. “One borer can fly as far as nine miles. A female borer lays as many as 300 eggs at a time.”

Longhorn borers are large, mottled insects 1 1/2 to 2 inches long. Their antennae are as long or longer than their bodies, Ferrara said.

He asked that residents with diseased trees call the nearest county Forestry Unit for assistance.

Researchers at the University of California, Riverside are studying natural predators that can safely be released into the environment to help stop the insect’s spread. But, Ferrara said, these studies are several years from completion.