The silverleaf whitefly (Bemisia argentifolii) has been a major pest in Arizona cotton (Gossypium hirsutum) since 1992. Typically, 4-10, or more, applications of insecticide have been used for its management in cotton for the past four seasons. The most effective, and therefore most widely used treatments, have been combinations of pyrethroid plus organophosphate or cyclodiene insecticides. The silverleaf whitefly and the closely related sweetpotato whitefly (Bemisia tabaci) have demonstrated a prodigious capacity to develop resistance to insecticides throughout the world. In 1994 monitoring data from Arizona showed one hundred-fold (100X) differences in susceptibility to key insecticides. Accordingly, a comprehensive integrated resistance management (IRM) plan for whitefly control in Arizona was prepared for implementation in 1995. The recommendations were supported by the Arizona Cotton Growers Association, the Arizona Cotton Research and Protection Council, the Arizona Department of Agriculture, Cotton Incorporated, the Southwest Whitefly Resistance Management Working Group, the Sticky Cotton Action Team, the United States Department of Agriculture, and the University of Arizona IPM Working Group. Despite the best efforts of the technical community and the industry, efficacy of the most effective insecticide treatments were lost in major cotton producing areas in Arizona in August and September 1995.