本文应用光镜及扫描电镜对大头金蝇、家蝇等幼虫的后气门进行了对照观察,证明后气门由体壁层、气门极层及连接于其下的气管3部份组成,在体壁层与气门极层之间为潜在性的气门腔。在光镜下只能看到气门板层上的结构,而扫描电镜可看到体壁层,其上也有3个长条形的气门裂,表面光滑,中间有闭合的缝隙。在每个气门裂的外侧缘上及内、中气门裂之间,共有4组气门肌(原称气门腺)。体壁层在气门肌的作用下可开闭,使空气进入或防止水的侵入。不同蝇种后气门体壁层上的气门裂、钮孔及气门肌的形态、数量、分布基本相似,仅气门肌的分枝数有所不同,而与气门板上各种结构的位置及形态并不一定相同。本文也观察了大头金蝇及棕尾别麻蝇一龄幼虫的后气门,证明都有2个气门裂,但发育尚未完全,几丁质化很差 In this paper, light microscopy and scanning electron microscopy of the gold flies, housefly and other larvae after the valve was observed after the valve, the valve is proved by the body wall layer, the valve layer and connected to the trachea under the 3 parts, in the body wall A potential valve chamber between the layer and the valve pole. In the light microscope can only see the structure of the valve plate layer, and scanning electron microscope can see the body wall layer, which also has three long strip of valve crack, the surface is smooth, the middle of a closed gap. In the outer edge of each valve crack and the inside, between the valve crack, a total of 4 groups of valve muscle (formerly known as valve gland). Body wall in the role of the valve muscle can be opened and closed, so that air into or to prevent water intrusion. The valve fissure, buttonhole and valve muscle morphology, quantity and distribution on the valve body wall of different fly species are basically similar, only the number of branches of the valve muscle is different, but with the position and shape of various structures on the valve plate Not necessarily the same. In this paper, we also observed the posterior valve of the golden flies and the first instar larvae of Fagaceae, showing that there are two valve fissures, but the development is incomplete and the chitinization is very poor