Invasion of the Blood Farmers (1972)
aka
Invasion der Blutfarmer
Invasion der Tollwütigen
Invasion of the Blood Farmers" is a B movie to treasure. It's overflowing with the kind of priceless ineptitude that makes movies like this so much damn fun. The acting, for the most part, is terrible, the dialogue is riotous, and the premise absolutely delicious.
It involves farmers who are also druids, harvesting the people of a rural area for their blood. Investigating the corpse of one person who managed to get away, scientist Roy Anderson (Norman Kelley) and his loyal student Don Tucker (Bruce Detrick) find that his blood is able to increase in amount on its own.
As they do their sleuthing, the Druid in Charge, Creton (Paul Craig Jennings) explains the whole motivation and plot just to make sure we get it. (IMDB Scott LeBrun )