Why couldn't they have brought Koalas too?

Sometime during the Gold Rush, around 1855 or so, the first Eucalyptus trees were introduced to California from Australia. In 1999, 144 years later, the red gum lerp psyllids (Glycaspis brimblecombei) were first found in California, followed by the spotted lerp psyllids in 2000. Eucalypts are valued trees in California, and probably feel like a natural part of the landscape to many. The Australian psyllids are insects that have infected and destroyed thousands of trees, and have even caused problems for birds that were feeding on the sugary substance produced by the insects. The red gum lerp psyllid has also been found in Florida.

Now Californians are fighting back against these insects, also known as "jumping plant lice." Introduction of a wasp as a biological control has not remedied the situation fast enough for some. The L.A. Times reports that the latest psyllid-fighting weapon is a tiny pesticide capsule, inserted in a hole drilled in an infected tree, that releases chemicals that kill the psyllids.