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Redgum Eucalyptus
Lerp Psyllid (RLP)
Last Updated: 08/02

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An adult Psyllid

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LERPS on Eucalyptus leaves
What do Redgum Lerp Psyllids look like?

The adult insects are small (1/8 inch long), slender and pale-green. They are sucking insects, can jump and fly, and are hard to see. Adults and larvae feed primarily on Redgum Eucalyptus trees. Mostly, what is seen are the sugar-like 1/8 inch wide white cones called "lerps." Larvae are found beneath these lerps or bumps they have built.

What damage do they do?

Both adults and especially larvae suck sap from the leaves and stems thus weakening Redgums. RLP produces large amounts of sticky clear liquid called honeydew which stains the ground beneath trees. A blackish sooty mold grows on the honeydew-covered surfaces. The lerps and honeydew stick to shoes and dirty cars, buildings and sidewalks. Heavy infestations are even more harmful causing leaf drop and severely stressing trees.

Why arethey a problem?

RLP occurs in Australia where it is not a problem because it most likely has natural enemies (small parasitic wasps) that normally keep them under control. RLP was introduced into California before 1998 without these natural enemies. RLP has become abundant in California because its favored host plants, certain species of eucalyptus trees, are commonly grown over much of California.

Can RLP be controlled?

Biological control for RLP offers the best hope for controlling this pest. On Wednesday, June 7, Dr. Donald Dahlsten, Center for Biological Control, University of California, Berkeley began an RLP biological control program by releasing a species of small parasitic wasp in Valley Village area of Los Angeles. This will be followed by field releases on a weekly basis at other monitoring sites in the county. We hope that the wasp, which is barely visible to the naked eye, will provide long-term control by feeding on larvae of RLP. In September 1999, Dr. Dahlsten brought back the small wasps from Australia, RLP's native home. Before releasing the wasps he first ensured that the wasp feeds only on RLP.

The parasitic wasp has been reared with amazing success in the quarantine facilities at Berkeley and it is hoped that they will thrive in California. It was also necessary to get background data on the numbers of RLP at the release sites so that Dahlsten and his team could have reasonable certainty that the parasites would be doing their job.

Once the parasites are released and if they become established, Dahlsten hopes that the parasitic wasp will gradually spread throughout the Los Angeles basin.

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