A plant extract from kudzu, Pueraria lobata (Willd.) Ohwi (Fabaceae), was tested as a UV protectant for the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), nucleopolyhedrovirus (SeMNPV), with and without the addition of an oil/emulsifier (cottonseed oil/lecithin) formulation. Aqueous and oil emulsion formulations of SeMNPV were applied to collards and the residual virus activity was determined for 7 d. Sunlight exposure of SeMNPV resulted in an activity loss of 42%, 85%, and 95% at days 2, 4, and 7, respectively. The addition of the oil/emulsifier to SeMNPV did not provide UV protection. At days 2, 4, and 7, activity losses were 67%, 84%, and 92%, respectively. Whereas the addition of kudzu (5%) to SeMNPV provided significant UV protection during the sunlight exposure period, activity losses of 17%, 62%, and 76% occurred at days 2, 4, and 7, respectively. The greatest UV protection for SeMNPV was achieved when cottonseed oil/lecithin were used in conjunction with kudzu. In this formulation, activity losses were 2%, 40%, and 55% at days 2, 4, and 7, respectively. Although the mode of action is currently unknown, the addition of cottonseed oil to kudzu resulted in an increase of both UVB (280 - 320 nm) and UVA (320 - 400 nm) absorbance.