There are thus two female openings, one for copulation, the other for oviposition, as well as a male opening.
The first act of the female after oviposition is to wrap her eggs in a casing of silk commonly called the cocoon.
So far as is known at present, all sticklebacks construct a nest for the reception or the spawn, which is jealously guarded by the male until the young are hatched, which event takes place in from ten to eighteen days after oviposition.
Their formation from buds which normally would have yielded leaves and shoots is explained by Parfitt as the outcome of an effort at fructification induced by oviposition, such as has been found to result in several plants from injury by insect-agency or otherwise.
Temporary oviducts are formed between the "spermduct" and the germinal epithelium at each oviposition.