Eucalypts in California lacked any exotic herbivore fauna for more than 150 years. Since 1985, however, a new pest species have been introduced in distinct clusters. The proposed research would characterize the native geographic range in Australia of all of the introduced species and identify specific regions of significant overlap among species in clusters. The areas of overlap in Australia would be matched with regions of high risk in California using the CLIMEX climate matching model. The patterns generated from the research would be provided to regulatory agencies to identify potential high risk routes of introduction from specific areas.