Topical bioassays of a carbamate (oxarnyl), three organophosphates (azinphosmethyl, malathion and methyl parathion) and a pyrethroid (cypermethrin) were conducted with the R. T. Gast Insect Rearing laboratory colony (GAST-LAB) and field-collections of boll weevils from several locations in Louisiana. The organophosphate azinphosmethyl (0.042 µg/weevil) and the pyrethroid cypermethrin (0.048 µg/weevil) were the most toxic insecticides to the GAST-LAB weevils followed by the organophosphate methyl parathion (0.083 µg/weevil), the carbamate oxamyl (0.313 µg/weevil) and the organophosphate malathion (0. 69,µg/weevil). Toxicological responses of nearly all of the field-collected weevils to most insecticides were not significantly different from the GAST-LAB colony. However, significantly higher LD(50)'s to cypermethrin (7x), azinphosrnethyl (2x) and malathion (3x) were found in two collections when compared to the GAST-LAB colony. Conversely, LD(50) values for oxamyl and methyl parathion were generally lower for the field-collected adults than for the GAST-LAB colony. Also the LD(50) values for oxamyl serve as reference values since no previous data were found in the literature.