Technical Abstract: Three oil adjuvants were evaluated in application tests against the boll weevil in the laboratory and field during 1997. The adjuvants in these tests were: once-refined cottonseed oil, and two horticultural mineral oils, Orchex 796 and WS2908 (Orches 796 formulated with a drift retardant). A series of aerial application tests of cyfluthrin and malathion ULV, which hcompared rates and types of oil adjuvants, were conducted. The first of these tests determined the effects of oil adjuvants on efficacy of malathion ULV. Ten ounces of malathion ULV per acre were applied in a total volume of 37 oz/a of adjuvant, with an application of undiluted malathion ULV as a standard. WS2908 had higher mortality than Orhex 796 which indicates that the addition of a drift retardant improves efficacy of Orchex 796. However, there was no difference in mortality between WS2908 and the undiluted application of malathion ULV. Cyfluthrin mixed in WS2908 8had mortality equivalent to the cottonseed oil treatment in all bioassays except at 2 DAT. Cyfluthrin mixed in Orchex 796 had the lowest mortality at 0 and 2 DAT. An evaluation of the rainfastness of these oil adjuvants in the field and laboratory showed that WS2908 had greater rainfastness than the other oil adjuvants. Malathion ULV was not as rainfast as cyfluthrin or fipronil.