Spermula (1976)
Spermula is a 1976 French-language horror movie directed by Charles Matton, with a running time of 1h 43m. It stars Dayle Haddon, Udo Kier and François Dunoyer.
The story is based around "spermulites", the alien inhabitants of a dying planet. The only way they can save their planet is by sucking the men of planet earth dry of sperm, kind of like horny vampires.