插入器（学名：），又名交尾刺、中叶突，阳茎器等，是雄性节肢动物 (主要是昆虫）的生殖器，与雌性动物交配时通过插入器来分泌由睾丸产生的精子。这个器官可以类比哺乳类动物的阴茎，尽管插入器的构造其实更为复杂。部分昆虫的插入器有荚包裹，就好像阴茎的包皮那样，但不叫“阴茎”，而是叫作“阳茎”。
“插入器”的学名“”源于古希腊语的η αιδώς（）或το αιδοίον（）、众数作τα αιδοία（）。
插入器是雄性昆虫腹部的一部分，即其整个身体三个主要部分的最后方的部分。插入器有生殖管连接往其体内的一对睾丸。插入器是雄性昆虫的阳茎的部分，其构造复杂，而且不同物种间会有不同的排列方式。complex and often species-specific arrangement of more or less sclerotized (hardened) flaps and hooks which also includes in some species the valvae (clasper), which are paired organs which help the male hold on to the female during copulation. During copulation, the aedeagus connects with the ovipore of a female. The aedeagus can be quite pronounced or .
The base of the aedeagus may be the partially sclerotized phallotheca, also called the phallosoma or theca. In some species the phallotheca contains a space, called the endosoma (internal holding pouch), into which the tip end of the aedeagus may be withdrawn (retracted). The vas deferens is sometimes drawn into (folded into) the phallotheca together with a seminal vesicle.
节肢动物的精子往雌虫传送时不会以液态 with free-swimming spermatozoa传送，而是contains capsules called spermatophores in which the actual spermatozoa are enclosed. In addition to the spermatophores, in some species the aedeagus also discharges a spermatophylax, a ball of 精弓nutritious secretions to aid the female in producing offspring.
鳞翅目的大多数雄性物种，其插入器均有鞘，which is supported by an organ called the juxta, which is located between the aforementioned valvae.
