They told us as much in the 2005 remake of War of the Worlds. The "aliens" hiding in the ground (D.U.M.B.s?) subsisted on human blood. The kicker? They all died from contaminated blood.
The aliens feeding on human blood wasn't invented for the 2005 movie. It was in the original H. G. Wells novel.
The aliens feeding on human blood wasn't invented for the 2005 movie. It was in the original H. G. Wells novel.