Although the regulation of reproductive diapause by environmental factors has been extensively studied in a variety of insect orders, sexual differences in the regulation of diapause are still poorly understood. We examined the effects of environmental factors including photoperiod, temperature and food on the regulation of reproductive diapause in both sexes of the rice bug Leptocorisa chinensis (Dallas) (Hemiptera: Alydidae) in the laboratory and under natural conditions. There was no significant difference in critical daylength (CDL) for diapause induction between the sexes. The CDL corresponded to the daylength in which development of the gonads was suppressed in half the insects caught in the field. Both sexes enter diapause at the same time in successive seasons. In diapause insects, on the other hand, there were sexual differences not only in retention of responsiveness to photoperiod and temperature but also in the food requirement, and these sexual differences lead to different timing of the resumption of reproductive development after overwintering. (C) 2007 Elsevier Ltd. All rights reserved.