Abstract: 【Aim】 Panorpidae, the largest family of Mecoptera, are important ecological indicators for environments. The immature stages of Panorpidae, however, are insufficiently studied so far mainly due to their strict ecological requirements and rearing difficulties. 【Methods】 The immature stages (including egg, larva, and pupa) of the scorpionfly Panorpa macrostyla Hua were studied biologically and morphologically using light and scanning electron microscopy. 【Results】 P. macrostyla is a univoltine insect, completing one generation per year. The adults appear from late June to early August. The egg is ellipsoid, with a raised reticulation on the chorion. The larva is eruciform, with three pairs of four-segmented thoracic legs and eight pairs of unsegmented prolegs. The larval head is strongly sclerotized, bearing a pair of compound eyes each comprising 26 ommatidia, a pair of 3-segmented antennae, and the mandibulate mouthparts. The larval trunk is cylindrical, bearing nine pairs of dorsal processes on the first nine abdominal segments and a single dorsal process on the tenth abdominal segment. A protrusible sucker is present on the terminal abdominal segment. The larval respiratory system is of the peripneustic type, having a pair of prothoracic and eight pairs of abdominal spiracles. The larval stage consists of four instars, and overwinters as prepupal stage within a pupal cavity in the soil. The pupa is exarate and decticous, morphologically similar to the adult. The male pupa has enlarged genital bulb on its caudal end. 【Conclusion】 The larvae of P. macrostyla are morphologically different from those of Neopanorpa, Sinopanorpa, Dicerapanorpa, and Cerapanorpa. However, P. macrostyla larvae differ from its congeners by the apical-expanded setae of L2 and SO2 on the head capsule, and D2, SD1, SD2 on the caudal segment, implying that the generic status of P. macrostyla needs further research.

Key words: Mecoptera, Panorpidae; , Panorpa macrostyla, life history, morphology, egg, larva, pupa