The Lower Rio Grande Valley (LRGV) has a long history of sweetpotato whiteflies (Bemisia tabaci) (SPW). SPW was first reported in the mid-1940's in the LRGV and continues through today. In 1990, the first severe, crop damaging infestations of SPW were reported in mid-Valley cotton fields. The fall of '90, found SPW completely destroying many of the more susceptible vegetable crops in the mid-Valley area. In the spring of 1991, SPW adults migrated in extremely large numbers from old vegetable plantings to cotton and started one of the most devastating, insect-damaging seasons on record for the LRGV. In excess of $ million were lost in yield, seed and insecticide expenditures in the area of highest infestation.