Insect Ravaging State’s Eucalyptus Trees

War has been declared by cities and scientists against a tiny beast that is ravaging eucalyptus trees across the state.

Alarmed by a population explosion among red gum lerp psyllids, insects that leave trees bald and sickly and excrete a sticky goo onto sidewalks and cars, nearly 100 scientists, city representatives and pest control experts converged in a Highland Park community center Wednesday to share information and strategies.

In the next month, Los Angeles plans to form a multi-agency task force to coordinate a regional attack on the one-eighth-inch insect, said George Gonzalez, chief forester for the Department of Public Works.

Red gum psyllids, first identified in Australia in the 1960s, were discovered in California about a year ago. Found first in El Monte, they have spread into San Diego, the Inland Empire and farther north than the Bay Area.

Although the insects have not yet killed any trees in the state, they cluster on leaves, block photosynthesis and cause a massive shedding of leaves. Young insects are covered by white, armor-like coverings called lerps that shield them from natural predators and common insecticides. An infected tree’s leaves are covered with lerps, which, from afar, look like a bad case of dandruff. Infected trees are more prone to attacks by insects such as borer beetles and diseases such as root rot that can kill them.

The psyllids are not as economically menacing as the medfly, which can destroy fruit crops, said Rosser Garrison, an entomologist with the Los Angeles County Department of Agricultural Commissioner/Weights and Measures. But there has been an enormous public outcry, because the damage they wreak is so visible.

At the Arboretum of Los Angeles County in Arcadia, which has the largest eucalyptus collection outside Australia with about 200 species and 1,000 trees, about a third of the eucalyptus--and 100% of the red gum variety--are infected with psyllids, said biologist Jerry Turney. The insects also are starting to attack a few other eucalyptus species.

In the San Fernando Valley, the epidemic is so severe that many trees appear close to dead, residents say.

“All the people do around here is sweep,” said Judy Jacob of Woodland Hills, referring to the fallen eucalyptus leaves. She wears a scarf when walking outdoors and leaves shoes outside because the goo sticks to hair and soles. “It’s disgusting,” she said.

Last month, the city of Los Angeles bombarded parks and some public streets with millions of ladybugs, a natural predator of psyllids and other insects, but that hasn’t worked well.

Part of the problem is that the psyllid scourge is new to this continent, and there has been little research, said Donald Dahlsten, professor and associate dean of the College of Natural Resources at UC Berkeley.

The most promising solution is a breed of tiny Australian wasps that feed exclusively on red gum psyllids, Dahlsten said. Within the next few weeks, he will go to Australia to bring the wasps--which do not harm humans--to California. But it could be months, perhaps a year, before the wasps clear state and federal regulatory hurdles, he cautioned, adding that even then, there’s no guarantee that what works in Australia will work here.

But after Wednesday’s meeting, some said they need more immediate answers.

“We’re getting questions every day from golf courses and homeowners associations,” said Paul Wizikowski, a representative from a fertilizer company. “Until the beneficial effects of these wasps come into effect, what do we do now?”

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Infesting Eucalyptus

The red gum lerp psyllid, native to Australia, has infested trees throughout Los Angeles County and the rest of the state.

DAMAGE TO TREES

The lerps are sticky and stain the ground underneath the trees. In severe infestations, thousands of lerps cover the ground, giving the appearance of fallen hail.

Sources: Rosser W. Garrison, Los Angeles County Agricultural Commission