【目的】 双委夜蛾Athetis dissimilis是近年来在我国农田新发现为害的一种害虫，明确其成虫活动节律和卵的孵化节律，可为其预测预报和防治提供依据。【方法】 在温度（25 ± 1）℃、相对湿度70% ±5%、光周期14 L∶10 D环境条件下，观察双委夜蛾的羽化、取食、交配、产卵等行为。【结果】 双委夜蛾雌虫、雄虫羽化主要发生在化蛹后第12天的光期，羽化高峰分别在13:00-17:00和13:00-15:00。取食行为主要发生在羽化后前2 d，且在暗期取食的个体数（47.08%）显著多于在光期取食的个体数（26.39%）。成虫的交配高峰在羽化后第3天，交配主要在暗期03:00-07:00进行，交配持续时间15-90 min, 平均47.33 min，以持续30-45 min的个体占比最高，达34.44%。羽化后第5天出现产卵高峰，产卵率达96.67%，产卵主要发生在暗期01:00-05:00。卵产出后第5天集中孵化，孵化率达92.04%，孵化高峰期在17:00-23:00，该时段累计孵化率64.99%。成虫羽化后第2天和第7天移动个体的比率较高，分别为9.72%和10.16%，每天进入暗期后移动率逐渐升高，进入光期后逐渐降低。不同日龄成虫在光期和暗期均出现较高比例的静息个体，前者平均为83.67%，后者平均为64.94%。【结论】 双委夜蛾成虫羽化、补充营养、交配、产卵、移动、静息等活动行为的昼夜节律明显，可作为其预测预报及防治的依据。

[Objectives]  To investigate the adult activity and egg-hatching rhythm of Athetis dissimilis, a recently discovered pest in Chinese farmland, and provide a basis for the prediction and control of this species. [Methods]  The eclosion, feeding, mating, oviposition, and other behavioral rhythms of A. dissimilis were observed at (25 ± 1)℃, 70% ± 5% relative humidity, under a 14L︰10D photoperiod. [Results]  Eclosion of female and male A. dissimilis generally occurred during the photophase on the 12th day after pupation, with the respective peaks of each sex occurring from 13:00 to 17:00 and 13:00 to 15:00. Adults mainly fed on the first 2 days after pairing, and more adults fed during the scotophase (47.08%) than during the photophase (26.39%). Moreover, most adults mated on the 3rd day after pairing, with the peak of mating activity occurring from 03:00 to 07:00 in the scotophase. Mating duration ranged from 15 to 90 minutes, with an average of 47.33 minutes, with most (34.44%) pairs mating for between 30 and 45 minutes. The peak of oviposition occurred on the 5th day after pairing when 96.67% of females laid eggs, the majority of which were laid from 01:00 to 05:00 during the scotophase. Most (92.04%) eggs hatched on the 5th day after oviposition. The peak of hatching was from 17:00 to 23:00, during which the accumulated hatching rate was 64.99%, significantly higher than that at any other time period. Adult mobility peaked on the 2nd and 7th day after pairing, with 9.72% and 10.16% of adults moving, respectively. The proportion of mobile adults gradually increased during the scotophase, then decreased during the photophase. The proportion of adults of all ages observed resting during the photophase and scotophase was 83.67% and 64.94%, respectively. [Conclusion]  The eclosion, feeding, mating, oviposition, hatching, moving and resting behaviors of A. dissimilis have an obvious circadian rhythm, information that can aid the forecasting and control of this pest.