An aedeagus ( or aedeagi) is a reproductive organ of male

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

s through which they secrete

sperm Sperm (: sperm or sperms) is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm ...

from the

testes A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of androgens, primarily testosterone. The ...

during

copulation Sexual intercourse (also coitus or copulation) is a sexual activity typically involving the insertion of the erect male penis inside the female vagina and followed by thrusting motions for sexual pleasure, reproduction, or both.Sexual inte ...

with a female. It can be thought of as the insect equivalent of a

mammal's penis A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation, and through which male placental mammals and marsupials also urinate. The term ''penis'' applies to many intromittent ...

, though the comparison is fairly loose given the greater complexity of insect reproduction. The term is derived . The aedeagus is part of the male's

abdomen The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...

, which is the hindmost of the three major body sections of an insect. The pair of

of the insect are connected to the aedeagus through the genital

duct The word duct is derived from the Latin word for ''led/leading''. It may refer to: * Duct (anatomy), various ducts in anatomy and physiology ** Tear duct, which carry tears to the eyes * Duct (HVAC), for transfer of air between spaces in a struct ...

s. The aedeagus is part of the male insect's phallus, a 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 An ovipore is a pore-like sexual organ of a female insect that is insemination, inseminated by the spermatophores ejected by the aedeagus of a male insect during copulation (zoology), copulation. The spermatophores that pass through the ovipore ar ...

of a female. The aedeagus can be quite pronounced or ''de minimis''. 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. In some

s, sperm is not passed to the female as liquid with free-swimming

spermatozoa A spermatozoon (; also spelled spermatozoön; : spermatozoa; ) is a motile sperm cell (biology), cell produced by male animals relying on internal fertilization. A spermatozoon is a moving form of the ploidy, haploid cell (biology), cell that is ...

, but as capsules called

spermatophore A spermatophore, from Ancient Greek σπέρμα (''spérma''), meaning "seed", and -φόρος (''-phóros''), meaning "bearing", or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especiall ...

s in which the actual spermatozoa are enclosed. In addition to the spermatophores, in some

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

the aedeagus also discharges a

spermatophylax A spermatophylax is a gelatinous bolus which some male insects eject during copulation with females through their aedeagi together with spermatophores, and which functions as a nutritive supplement for the female. See also *Nuptial gift Formall ...

, a ball of

nutritious Nutrition is the biochemical and physiological process by which an organism uses food and water to support its life. The intake of these substances provides organisms with nutrients (divided into macro- and micro-) which can be metabolized t ...

secretions, as a

nuptial gift Formally, a nuptial gift is a material presentation to a recipient by a donor during or in relation to sexual intercourse that is not simply gametes in order to improve the reproductive fitness of the donor. Often, such a gift will improve the fit ...

to aid the female in producing offspring. In males of most species of

Lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...

, the aedeagus has a sheath which is supported by an organ called the

juxta In insect anatomy, the juxta is an organ in the males of most Lepidoptera (i.e. moths and butterflies) that supports the aedeagus, the organ used for reproduction in insects. The juxta is located between the two valvae. Juxta has also been use ...

, which is located between the aforementioned valvae.

References

{{reflist Animal reproductive system Sex organs Insect anatomy