【目的】 凹唇壁蜂Osmia excavata是我国重要授粉昆虫之一，在北方果树授粉中有极其重要的作用。凹唇壁蜂蛹期是成虫各组织器官形成、生长发育和生殖系统发育成熟的关键时期。本研究旨在探讨凹唇壁蜂蛹期的发育历期、形态特征、生殖器官的辨别及体型的测定。【方法】 取化蛹至成虫羽化期间的蜂茧，解剖选取复眼颜色发育一致的凹唇壁蜂，进行室内观察和拍照。【结果】 凹唇壁蜂蛹期发育过程中复眼颜色变化明显，从粉色、褐色、褐黑色到黑色。粉色复眼蛹发育至褐色复眼蛹的平均历期为（7.00±0.13）d，褐色复眼蛹发育至褐黑色复眼蛹的平均历期为（6.57±0.17）d，褐黑色复眼蛹发育至黑色复眼蛹的平均历期为（7.13±0.21）d，黑色复眼蛹至头胸部出现黑色的平均历期为（8.54±0.24）d。凹唇壁蜂蛹期变化主要为复眼颜色、外部形态结构、体表颜色及卵巢和精巢出现。当复眼颜色发育至黑色时，雌蜂体重明显大于雄蜂体重（P < 0.01），雌蜂体型较大，腹部末端较为尖锐，有突出的产卵瓣，2个卵巢左右对称，每个卵巢有3根卵巢管；雄蜂体型较小，腹部末端较为圆钝，无突起，精巢左右各一，合并成“Y”型，精巢和卵巢均呈白色透明状。【结论】 凹唇壁蜂蛹期内部各组织器官和外部形态发生巨大变化，从预蛹形态逐步发育为成虫形态，各组织器官从无到有，其生长和发育逐渐成熟。本研究探明了凹唇壁蜂蛹期各阶段发育时间及其形态变化特征，明确了蛹期雌性和雄性的形态差异、体重以及卵巢和精巢的形态特征，为深入研究凹唇壁蜂器官生长、分化和发育奠定了基础。

 [Aim]  Osmia excavata is one of the most important pollinators in China, playing a crucial role in the pollination of fruit trees in the northern regions of the country. The pupal stage is a critical period for the formation of tissues and organs, growth, and development, and reproductive system maturation in adults. This study aims to investigate the developmental duration, morphological traits, reproductive organs, and the body mass of O. excavata during the pupal stage. [Methods]  The cocoons were carefully extracted and bees sharing the same compound eye color were dissected in the laboratory for analysis. [Results]  The results showed that the color of the compound eye of O. excavata changed significantly during the pupal stage, transitioning from pink to brown, brown to black, before ultimately becoming black. The average duration of the transition in eye color of O. excavata pupae was (7.00±0.13) d from pink to brown, (6.57±0.17) d from brown to brown-black, and (7.13±0.21) d from brown black to black. The average duration from a black-eyed pupa to the development of a black head and thorax was (8.54±0.24) d. The primary transformations seen during the pupal stage included changes in the compound eye color, external morphological structure, body surface color, and ovary and testicle structures. The weight of female bees is significantly more than male bee when the color of the compound eye turned black (P < 0.01), the female bee is larger, the end of the abdomen is more sharp, there are prominent oviposition petals, the two ovaries are symmetrical, and each ovary has three ovarian tubes; The male bee is small, the end of the abdomen is relatively round and blunt, there is no bulge, the left and right of the sperm nest, merge into a “Y” shape, and the sperm nest and ovary are white and transparent. [Conclusion]  The pupal stage of O. excavata undergoes significant internal and external changes during development. As it develops from the pre-pupa to the adult stage there is a gradual development of the internal tissues and organs, as well as changes in the external morphology. Our research investigated developmental duration and morphological changes during the pupal stage of O. excavata. We identified differences in morphological traits, body mass, and the morphology of ovaries and testes between females and males throughout this phase. Our findings establish the foundation for comprehensive research into organ growth, differentiation, and development in the solitary wasp, O. excavata.