Beetles Threaten Eucalyptus on Catalina

An aggressive Australian beetle that has destroyed hundreds of eucalyptus trees throughout Southern California has spread to Santa Catalina Island, where 90% of the non-indigenous trees are eucalyptus.

Catalina has “quite an infestation,” said Paul Rippens, senior deputy forester for the Los Angeles County Fire Department. During an inspection recently to see whether the pest had reached the island, Rippens said he found the insect in dozens of eucalyptus trees, which now must be destroyed.

The beetle presents a particular threat on Catalina Island, Rippens said. Nearly all of the trees that were planted on the island are eucalyptus, he said, and an irrigation method normally used to keep the insect away from healthy trees is impractical there because of a water shortage. In fact, the shortage is a major reason for the popularity of the tree, which normally survives on little water.

“Because water is so expensive on the island, few trees are watered,” Rippens said, except at Wrigley Memorial and Botanical Garden. As a result, he said, “many of the trees are under a lot of stress, and get cracks in their bark. The beetle has the ability to pick out the weakest trees.”

The voracious beetle, known as the eucalyptus longhorn borer, was probably brought to the island more than a year ago, Rippens said, judging by the number of trees affected. He speculated that it came in a load of eucalyptus firewood.

The infestation is already widespread, according to Doug Propst, president of the Santa Catalina Island Conservancy, the agency that owns 86% of the rugged island. “I think they’re pretty much across the island, at the isthmus, at Two Harbors and here in Avalon,” he said. “We’re having a pretty dry year now, and that makes the trees even more susceptible.”

Several independent entomologists were to examine the island’s eucalyptus trees, Propst said. Then the conservancy will meet with forestry officials to decide how to attack the problem, he said.

The borer beetle, which is indigenous to Australia, was first found in Southern California in 1984 in wood that had been shipped from Australia to an El Toro lumber yard in Orange County.

The insect has since destroyed eucalyptus trees from San Diego County to Ventura County and into San Bernardino and Riverside counties, forestry officials said. Adult beetles can fly up to nine miles during migration, which occurs at night.