【目的】 基于黄脊竹蝗Ceracris kiangsu若虫不同龄期各形态特征的差异，探讨黄脊竹蝗若虫期的最佳分龄指标，明确Dyar法则和Crosby法则在黄脊竹蝗若虫龄期划分上的适用性，为直翅目昆虫若虫龄期划分提供理论依据。【方法】 自竹蝗卵孵化后，单头饲养于养虫室内，测定每一龄黄脊竹蝗若虫的体长、体重、头长、头宽、翅芽长、翅芽宽、翅芽面积及触角长8个形态指标，采用频次分布、Brooks指数、Crosby指数以及回归拟合方法筛选出最佳的分龄指标，同时通过逐步判别分析法构建龄期判别函数。【结果】 黄脊竹蝗若虫有5龄，雌若虫和雄若虫的龄数相同；各形态指标频次分布显示头长和头宽呈现5个集中分布区，翅芽宽和翅芽面积有3个集中分布区。Brooks指数在1.09和3.86之间，呈现出随着虫龄增大而减小的趋势。Crosby指数均大于0.1，黄脊竹蝗若虫形态发育特征不符合Dyar法则和Crosby法则。8个形态指标和虫龄间线性、多项式拟合度较好。线性拟合中，头宽与龄期的决定系数最大（R² = 0.933 5）；多项式拟合中，翅芽长与龄期的决定系数最大（R² = 0.978 9）。【结论】 头宽是黄脊竹蝗若虫分龄的有效指标，头长和体长次之，黄脊竹蝗分龄指标适合在监测与防治中应用。

[Objectives]  To determine the optimal morphological characteristics for identifying nymphal instars of the yellow-spined bamboo locust, Ceracris kiangsu (Orthoptera: Arcypteridae), examine the applicability of Dyar and Crosby rules to this species, and provide a theoretical basis for determining the nymphal instars of Orthopterans based on the variability of morphological characteristics of different developmental stages. [Methods]  Nymphs were reared in an insectary after hatching. Eight morphological variables, including body length, body weight, head length, head width, wing bud length, wing bud width, wing bud area and antennal length, were measured and analyzed statistically for each instar. [Results]  Five instars were distinguished without gender differences. Five distribution peaks were apparent based on head length and head width, and three concentrated distribution areas for wing bud width and wing bud area were apparent after frequency analysis. The Brooks’s ratio ranged from 1.09 to 3.86, and decreased with increasing instar. The Crosby’s ratio was over 0.1. The growth dynamics of morphological variables were not consistent with Dyar and Crosby rules. The relationship between nymph instars and the eight measured morphological variables closely approximated a polynomial regression. The linear coefficient of determination of head width had the maximum value R² = 0.933 5, and the quadratic and cubic coefficients of determination of wing bud length had the maximum value R² = 0.978 9. [Conclusion]  Head width is the optimal variable for distinguishing the nymphal instars of C. kiangsu, followed by head length and body length. All three variables can be used in pest monitoring and control.