GO:0042628

The deposition of a plug of sperm or other gelatinous material into the opening of the vulva by a male at the termination of copulation. Probably acts to prevent subsequent matings by other males. [GOC:jl, http://www.wildcru.org/glossary/glossary.htm, http://www.wormatlas.org/glossaries/cglossary.htm, PMID:11267893]