Over the years, Timothy Paine, professor in the UC Riverside Department of Entomology, has become increasingly convinced that someone or some group has brought a series of pests from Australia to California to get rid of California's eucalyptus trees, according to a story on NPR's All Things Considered.

"You can find alternative explanations for all of this, no question about it," Paine said. "This is something we think is likely to have happened, but we don't have a smoking gun."

Paine's suspicions were raised by introductions of 16 eucalyptus pests over the past 25 years. The...