The objective of this study was to investigate the effects of microwave radiation on Callosobruchus maculatus (Fabr., 1775) pupae in the cowpea (Vigna unguiculata) cultivars BRS Paraguaçu and BRS Xique-xique. The irradiation was made using a commercial microwave oven with a 2450 MHz frequency, 800 W power output, in low power (30%), with exposure periods to microwave radiation of 0, 60, 90, 120 and 150 seconds. It was observed, for both cultivars, reduction of the number of insects emerged per grain, number of insects emerged per treatment and increase in the egg to adult period, with 60 seconds exposure to microwave radiation. The 90, 120 and 150 seconds exposure periods to microwave radiation were lethal to 100% of the C. maculatus pupae. [ABSTRACT FROM AUTHOR]