Here Comes the Red Gum Lerp Psyllid
by Fred Hoffman
For the last five years, agriculture officials around the state have been monitoring the advance of the redgum lerp psyllid, an insect that has quickly spread from initial sightings in the leaves of eucalyptus trees in El Monte and Fremont. And now we have them here, too.
The Adult Redgum Lerp Psyllid
Most noticeable on the redgum variety of eucalyptus (Eucalyptus camaldulensis), this small, fly-like insect - usually yellow or green in color, about an eighth of an inch long - is recognizable by its "lerp", a white, crystallized structure of honeydew on the underside of the leaves, which serves as protection for the larvae. The damage this sucking insect causes is quite noticeable: massive leaf drop along with sticky honeydew secretions, a mess for windshields and shoe bottoms alike. This premature defoliation of the trees could eventually weaken and destroy an infected eucalyptus. Experts guess that an unwitting traveler brought the redgum lerp psyllid to the U.S. from Australia, perhaps as a hitchhiker on a wreath made of eucalyptus leaves.
The Immature Redgum Lerp Psyllid
So, what can be done to battle this pest from Down Under? Unfortunately, at this time, not much. Experts, including U.C. researcher Dr.Donald Dahlsten, are now combing Australia, the original home of the eucalyptus tree, for a predatory wasp, one of the psyllid's natural enemies. In the meantime, a couple of native lady beetle varieties are munching on the psyllids here, offering some more natural control.
These are the "lerps" - protective shells for the redgum psyllids
If you spot those distinctive, white crystals on the underside of your redgum eucalyptus, a strong blast of water from your hose can help dislodge them. Making sure your trees are getting summer water can help keep the tree healthy. Most of the damage appears limited to the redgum variety, with some sporadic outbreaks on others where it does less damage. A good piece of insurance: avoid planting the redgum eucalyptus. Also - and this is true whenever you're thinking of installing a lot of one kind of tree or shrub - plant several different varieties to reduce the chances of a pest or disease playing havoc with all your hard work. And when traveling to a foreign country, fight the urge to return with any fruit or plant material.
Thanks to Dr. Don Dahlsten, U.C. Researcher, for the pictures. For more information about the redgum lerp psyllid, visit his website:
http://www.cnr.berkeley.edu/biocon/dahlsten/rglp/RLP_Main.htm
REDGUM LERP PSYLLID UPDATE:
U.C. Berkeley environmental science professor, Dr. Donald Dahlsten, returned in early September from Australia (where the eucalyptus tree and the lerp psyllid originated), with a friend in hand. There, Dahlsten discovered a small, parasitic wasp that attacks the psyllid by laying its eggs inside the insect, killing it.
It could take a year or more before it's known whether the wasps, currently in quarantine at UC Berkeley, will be released in California. Dahlsten is hopeful they will prove safe. He believes the wasps feed only on lerp psyllids, but says it remains to be proven that they won't pose a danger to other insects. "Everybody wants the parasites," said Dahlsten. "Especially people in Los Angeles have been pressing me, saying, 'we need to release right away,' but I won't do this. We need to make sure it's safe. "