The objective of our study was to evaluate the natural history of facultative interactions with the exotic ant-plant Ricinus communis (L.) across habitats in both southern California and Costa Rica. Specifically, we examine the following questions: (1) What is the variability of plant architecture (Leaf size and herbivory, EFN size and abundance) across all habitats?; (2) Is there a relationship between ant diversity, EFN variability and plant herbivory?; and (3) Does ant-exclusion have an effect on herbivory across all habitats? We are currently analyzing the Costa Rica data, and have partially completed the analysis of the California data. In California, we have only observed Argentine ants (Linepithema humile) visiting Castor Bean plant EFNs. Castor bean plants located in canyons have larger leaves, smaller EFNs and more herbivory, while plants located near well-watered areas (gardens) have smaller leaves, larger EFNs and less herbivory. We also did not detect a significant relationship between EFN size and herbivory. Currently, our California ant-exclusion experiment is still active and will be ready for data collection and analysis in approximately one month.