The oriental armyworm, Mythimna separata (Lepidoptera: Noctuidae) is a harmful pest which causes heavy loss in agricultural crops. Sex identification of M. separata is very important for understanding the biology and management of this pest. Development of fast and convenient methods to identify M. separata female and male is the necessary prerequisite for conducting gender-related studies. In this study, new methods to differentiate sex of M. separata at pupal and adult stages were investigated. Our results showed that posterior abdominal segments containing genital organs which are morphological traits to differentiate female and male. Genital openings are important characters for the female and male pupae differentiation. For female pupa, it locates on the ventral side of eighth and ninth abdominal segments and appears as a visible longitudinal suture; for male pupa, it locates on the ventral side of the ninth abdominal segment and appears as a short slit surrounded by a pair of visible semicircular lumps. Bristle numbers are another indicator for sex differentiation of adults. Each female has three-bristled frenulum and each male has one bristled-frenulum near the base of hind wing of each side of moth body. We confirmed the two sex differentiation methods manually by dissecting genitalia of adults and found their genger was as same as what we examined the sex of pupae and adults using the morphological methods.

东方粘虫Mythimna separata（鳞翅目：夜蛾科）是一种有害害虫，会造成农作物的严重损失。分离分枝杆菌的性别鉴定对于理解该害虫的生物学和处理非常重要。发展快速，便捷的方法来鉴定分离的分枝杆菌是男性和性别研究的必要前提。在这项研究中，新的方法来区分分离的分枝杆菌在p和成年阶段进行了调查。我们的研究结果表明，腹部后段含有生殖器官，这是区分女性和男性的形态特征。生殖器开口是雌性和雄性important分化的重要特征。对于雌性，它位于第八和第九腹部的腹侧，并显示为可见的纵向缝线；对于雄性pa，它位于第九个腹部的腹侧，表现为一条短缝，被一对可见的半圆形肿块围绕。鬃毛数量是成年人性别分化的另一个指标。每只雌性有三毛刚毛的系带，而每只雄性有蛾毛体两侧后翅的底部附近有一个刚毛的毛发带。