Efforts to remove some of California's 40,000 "Eucalyptus" trees have been met with a mixed reaction from the public, and there have been protests against removal. Removing "Eucalyptus" trees can be expensive and often requires machinery or the use of herbicides. The trees struggle to reproduce on their own outside of the foggy regions of Coastal California, and therefore some inland "Eucalyptus" forests are predicted to die out naturally. In some parts of California, eucalypt plantations are being removed and native trees and plants restored. Individuals have also illegally destroyed some trees and are suspected of introducing insect pests from Australia which attack the trees.