2005 Annual Report 4d.Progress report. This report documents research conducted under a Reimbursable Agreement between ARS and The Bureau of Land Management. Additional details of the research can be found in the report for the parent project 5325-22000-020-00D, Biology and Management of Invasive Weeds in the Western US. Biological control of several invasive weeds of the western United States has been proposed as one of the only cost effective methods to management species like saltcedar, broom and yellow starthistle and thus this project was continued with the Bureau of Land Management to expand the potential of this technology for key target species important to both agencies. The USDA-ARS Exotic and Invasive Weeds Research Unit of Albany, CA, in cooperation with the Biological Control of Weed Project at Temple, TX, and the European Biological Control Laboratory in Montpellier, France, have identified, colonized and are now testing new natural enemies of these target weeds. A leaf beetle, Diorhabda elongata, that attacks saltcedar has been imported, tested and released into several western states where it is highly impacting the target weedy shrub, while natural enemies of the other key invasive weeds previously mentioned are still under quarantine testing and evaluation. Beetles from China worked well in some areas of the country but in California and Texas this agent did not establish, spread or significantly impact the target saltcedar. A new similar leaf beetle from Crete, Greece has now been tested and released to increase biological control effectiveness in California, Texas and other more southern locations. The agents released to now seem to be effective causing defoliation of the target weeds across the release areas but have not yet spread to significant levels nor caused extensive defoliation as has occurred in other locations. These beetles are being evaluated using extensive monitoring techniques that have identified beneficial impacts that are sure to aid land managers in controlling weeds through biologically-based integrated weed management efforts. If successful, this project should provide cost effective long term control is these new locations.