Definition: Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.
Input: Individuals have also illegally destroyed some trees and are suspected of introducing insect pests from Australia which attack the trees.

Individuals have also illegally killed some trees. They may have brought insect pests from Australia which attack the trees.