Captive (1980)

aka: Fruktans Offer/Prisoners Of Styrolia

Earth and the planet Sthyrolia are at war over the possession of valuable Dirathium crystals. A Styrolian warship is shot down on Earth and the surviving aliens make their way to a nearby farmhouse where they take the family captive. With David Ladd, Cameron Mitchell and Lori Saunders of Petticoat Junction fame.