The ovipositor is a tube-like organ
used by some animal
s, especially insects for the laying of eggs
. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typically its form is adapted to functions such as preparing a place for the egg, transmitting the egg, and then placing it properly. For insects, the organ is used merely to attach the egg to some surface, but for many parasitic
species (primarily in wasp
s and other Hymenoptera
), it is a piercing organ as well.
Some ovipositors only retract partly when not in use, and the basal
part that sticks out is known as the scape, or more specifically oviscape, the word ''scape'' deriving from the Latin word ''scāpus
'', meaning "stalk" or "shaft".
s use their ovipositors to force a burrow into the earth to receive the eggs. Cicada
s pierce the wood
of twigs with their ovipositors to insert the eggs. Sawflies
slit the tissues
s by means of the ovipositor and so do some species of long-horned grasshoppers
. In the ichneumon wasp genus ''Megarhyssa
'', the females have a slender ovipositor (terebra) several inches long that is used to drill into the wood of tree trunks
. These species are parasitic in the larva
l stage on the larvae of horntail
wasps, hence the egg must be deposited directly into the host's body as it is feeding. The ovipositors of ''Megarhyssa'' are among the longest egg-laying organs (relative to body size) known.
s of the Aculeata
(wasps, hornets, bees, and ants) are ovipositors, highly modified and with associated venom gland
s. They are used to paralyze prey, or as defensive weapons. The penetrating sting plus venom allows the wasp to lay eggs with less risk of injury from the host. In some cases the injection also introduces virus particles that suppress the host's immune system and prevent it from destroying the eggs. However, in virtually all stinging Hymenoptera
, the ovipositor is no longer used for egg-laying. An exception is the family Chrysididae
, members of the Hymenoptera, in which species such as ''Chrysis ignita
'' have reduced stinging apparatus and a functional ovipositor.
ovipositors have specialized serrated teeth to penetrate fruits, but gall wasp
s have either uniform teeth or no teeth on their ovipositors, meaning the morphology
of the organ is related to the life history.
Members of the Diptera
n (fly) families Tephritidae
have well-developed ovipositors that are partly retracted when not in use, with the part that sticks out being the oviscape. Oestridae
, another family within Diptera, often have short hairy ovipositors, the species ''Cuterebra fontinella
'' has one of the shortest within the family.
Ovipositors exist not only in winged insects
, but also in Apterygota
, where the ovipositor has an additional function in gathering the spermatophore during mating. Little is known about the egg-laying habits of these insects in the wild.
Female bitterlings in the genus ''Rhodeus
'' have an ovipositor in the form of a tubular extension of the genital
orifice. During breeding season, they use it when depositing eggs in the mantle cavity of freshwater mussel
s, where their eggs develop in reasonable security. Seahorse
s have an ovipositor for introducing eggs into the brood pouch of the male, who carries them until it is time to release the fry into a suitable situation in the open water.
File:Urophora.cardui.female.jpg|A female fly in the family Tephritidae, with the ovipositor retracted and only the scape showing.
File:Anastrepha ludens 1322089.jpg|Ovipositing Mexican fruit flies showing the scapes of the extended ovipositors.
File:Megarhyssa.jpg|Female ''Megarhyssa'' laying eggs with her ovipositor.
Category:Animal reproductive system