【目的】 为明确界定豌豆修尾蚜Megoura crassicauda的虫龄，以期达到准确、快速识别豌豆修尾蚜龄期的目的。【方法】 利用体式显微镜分别对豌豆修尾蚜不同翅型、不同龄期体长和体色、体宽、头宽、触角长度、后足胫节长度、腹管长度、尾片形状和长度7项指标进行观察与测量。【结果】 在豌豆修尾蚜的不同虫龄中，7项形态指标均存在显著差异（P<0.05）。无翅型与有翅型个体的触角长度在不同虫龄间无重叠，可作为龄期鉴定的重要指标。体长和后足胫节长可作为辅助指标。此外，翅芽发育程度可用于区分3龄和4龄若蚜，尾片形状可用于区分若蚜和成蚜，触角亚节的数量可以作为区分1龄、2龄若蚜与其他龄期蚜虫的典型特征。【结论】 用触角长度作为豌豆修尾蚜龄期鉴定的首要指标，再结合触角节数的变化、体长和体色、后足胫节长、尾片形状和翅基的发育程度等指标，准确且高效地鉴定不同龄期豌豆修尾蚜。

[Aim]  To develop an accurate and rapid method for identifying instars of the aphid Megoura crassicauda. [Methods]  A stereo microscope was used to record the body length and body color, body width, head width, antenna length, hind tibia length, cornicle length, and caudal shape and length, of different M. crassicauda instars. [Results]  Seven morphological indicators differed significantly among different instars (P<0.05). The antennal length of apterous and alate individuals from different instars did not overlap, and can therefore be used to definitively identify instars. Body length and hind tibia length can be used as auxiliary indicators. In addition, the presence of wing buds, the shape of the cauda, and the number of antennal subsegments, can also be used for rapid and specific instar identification. [Conclusion]  Antenna length can be used as the primary means of identifying the instars of M. crassicauda. When this is combined with the number of antennal segments, body length and color, hind tibia length, and the shape of caudal and wing bases, it is possible to accurately and efficiently identify the different instars of this species.