B-type Bemisia tabaci, known commonly as the 'silver leaf white fly' is in Australia and becoming more widespread. The silver leaf whitefly was first detected in Australia in October 1994. It is now established in the Northern Territory, Queensland and New South Wales. This species damages crops through the effects of its feeding, through the effects of the honeydew it produces, which causes moulds on leaves and contaminates cotton lint, and through the spread of geminiviruses. Among the geminiviruses of potential concern to the cotton industry is the cotton leaf curl virus currently causing serious problems in cotton producing regions of Pakistan. Two other whitefly species are often encountered in cotton regions, the native Bemisia tabaci and the greenhouse whitefly, Trialeurodes vaporariorum. A recent brochure &quote;Silver leaf Whitefly: A potential problem for Australian crops&quote;, produced by the CSIRO Division of Entomology, illustrates and describes the differences between these whitefly species(copies can be obtained from Dr De Barro). Overseas, the silver leaf whitefly has rapidly developed resistance to a wide range of insecticides. Given these experiences, and the evidence that the B biotype in Australia is resistant to organophosphate, carbamate and many synthetic pyrethroid insecticides (Robin Gunning, NSW Agriculture pers. comm), sole reliance on chemical insecticides is unlikely to lead to long term control. The common experience in areas where such a situation has prevailed has been the rapid selection of populations that are resistant to the insecticides applied. This is true not only for the conventional insecticides but also for the new novel chemistries such imidacloprid, buprofezin and pyriproxifen. In such circumstances, management becomes extremely difficult. In contrast, in regions where insecticides have not been the sole means of control, natural enemies, both introduced and native, have proven to be effective in reducing damage.