The Silverleaf whitefly (SLWF) was first found in the San Joaquin Valley, in some cotton fields near Bakersfield, in 1992. Since then it has expanded throughout the Valley usually at low to moderate levels but occasionally at levels high enough to cause economic damage. This study looked at whitefly population growth from 1994 through 1996 using three inch by three inch yellow sticky cards along four east-west valley transects. SLWF populations in the San Joaquin Valley were higher and more widespread in 1996 then in the other two years. Populations of SLWF were lowest in1995, possibly due in part to a much cooler, wetter spring and the influence of high numbers of other pests. Distribution along east-west lines was not similar for all the trap lines but instead seemed to be related to local geographical features such as proximity to foothills and crop makeup and diversity.