Abstract: 【Aim】 The leafminer Chromatomyia horticola (Goureau) is one of the most important pests commonly found on vegetables in China. Up to now, there has been no systematic study of the morphology of the preimaginal (egg to pupa) stages of C. horticola. 【Methods】 We collected eggs, larvae of different instars and pupae from the field and reared in the laboratory. The morphological characteristics of the preimaginal stages of C. horticola from egg to pupa were observed and described systematically, and the larval instars were divided by measurement of the length of mouth hooks and cephalopharyngeal skeleton. 【Results】 We reported the pneustocera of egg for the first time for C. horticola which also for the family Agromyzidae. The larvae were divided into three instars based on the length of mouth hooks and cephalopharyngeal skeleton. The morphological characteristics of different larval instars were described. The precise method by measurement of skeleton structures and the fast method by observation of external morphology were established for discrimination of different larval instars of C. horticola. The development of the pupa was divided into five stages significantly based on morphological characteristics. 【Conclusion】 This study described the morphological characteristics of the preimaginal stages and divided the larval instars of the C. horticola, which provides fundamental information for the study of the morphology of preimaginal stages of agromyzids and the biology, physiology and control of C. horticola.

Key words:  Chromatomyia horticola, morphology, preimaginal stage, pneustocera, larval instar