【目的】 旨在明确草地贪夜蛾 Spodoptera frugiperda 在湖北玉米田的种群动态及扩散规律，为该虫的预测预报和科学防控提供依据。【方法】 分别在武汉、荆州和襄阳的春、夏、秋玉米田，采用五点取样法调查草地贪夜蛾幼虫种群数量；在玉米田人工接虫，调查幼虫扩散情况。【结果】 种群调查结果显示，草地贪夜蛾幼虫在春玉米田（武汉）从大喇叭口期开始发生，抽雄期出现虫量高峰[（3.58±0.56）头/百株]，腊熟期无发生。在夏玉米田（武汉、荆州、襄阳）从拔节期开始发生，最大虫量出现在荆州玉米抽丝期[（51.39±4.62）头/百株]，襄阳玉米腊熟期还有幼虫发生。在秋玉米田（武汉、荆州）从苗期至腊熟期均有发生，最大虫量出现在荆州玉米抽丝期[（25.00±2.61）头/百株]。扩散试验结果显示，以接虫株为中心，草地贪夜蛾幼虫可向周围植株扩散为害。幼虫转株扩散多在2、3、4龄幼虫期发生，且3龄时新增扩散株比例显著高于2龄期和4龄期。初孵幼虫密度为150头/株时，整个幼虫期扩散距离为（352.50±17.02）cm，约为10头/株的3.5倍。扩散实验期间，以东风的天数最多（占比达40%），幼虫沿着东风向西扩散的比例为60.32%，显著高于其它方向。【结论】 草地贪夜蛾幼虫在湖北春、夏、秋玉米田均有发生，虫量高峰多出现在玉米抽雄、抽丝期。草地贪夜蛾幼虫的转株扩散在3龄期最盛，扩散距离随幼虫密度的增加而变远，且多沿顺风方向扩散。

[Objectives]  To improve the forecasting and control of the fall armyworm, Spodoptera frugiperda in maize fields. [Methods]  The five-spot sampling method was used to monitor the fall armyworm larvae population in spring, summer and autumn, maize crops were in Wuhan, Jingzhou and Xiangyang cities. Dispersal of larvae was investigated by experimentally infesting maize crops with newly hatched larvae. [Results]  Larvae began to occur during the big-bell mouth stage in spring maize fields in Wuhan, peaked during the tasseling stage [(3.58 ± 0.56) larvae per 100 plants], and were not detected in the dough stage. In summer maize crops, larvae began to occur during the jointing stage. Larval density was highest during the silking stage in Jingzhou [(51.39 ± 4.62) larvae per 100 plants], and some larvae were still alive in the dough stage in Xiangyang. Larvae were present from the seedling stage to the wax-ripening stage in autumn maize crops in Wuhan and Jingzhou but peak numbers were observed during the silking stage in Jingzhou [(25.00±2.61) larvae per 100 plants]. The results of the dispersal experiment indicate that larvae gradually disperse from the release point to surrounding maize plants with dispersal taking place during the 2nd, 3rd and 4th instars. Significantly more plants were colonized by 3rd instar larvae than by 2nd and 4th instar larvae. At an initial density of 150 newly hatched larvae per plant, the horizontal dispersal distance of the entire larval stage was (352.50 ± 17.02) cm; about 3.5 times that with an initial density of 10 larvae per plant. Easterly winds were the most common (40%) during the period of larval dispersal, and 60.32% of larvae moved westward, significantly more than moved in other directions. [Conclusion] Fall armyworm larvae occur in spring, summer and autumn maize crops, and reach peak abundance in the tasseling and silking stages. 3rd instar larvae disperse the most and the dispersal distance if the initial larval density was higher. The majority of larvae dispersed downwind.