1 The ability to quantify whitefly migration provides a tool that can contribute to an improved understanding of the epidemic development of whitefly-transmitted viruses.

2 In an attempt to develop a protocol for estimating whitefly immigration and emigration rates in an annual crop, new traps and sampling devices were tested in the field and models for population dynamics were developed.

3 An estimate of immigration rate was derived from the growth of a natural population of Trialeurodes vaporariorum (Westwood) in the beginning of a crop cycle before offspring of immigrants contributed to population growth.

4 A model for changes in whitefly density during an entire bean (Phaseolus vulgaris L.) crop cycle, including an immigration parameter, was also developed.

5 Non-attractant window traps surrounding an annual field crop were assumed to intercept whiteflies immigrating into and emigrating away from the crop. Captures on these traps could not categorically be identified as immigrants or emigrants, but the cumulated captures nevertheless explained 66% of the variation in population density found within the field. Hence, window traps may be used as an efficient and reliable alternative to yellow sticky traps, aspirator methods and leaf-turn methods, etc., for estimating whitefly densities in field crops.