I'm trying to remember a film about dead grasshoppers from space that were found in a British subway. Likely made in the late 50s or 60s. I remember there was a terrible noise that emanated from the area the creatures were discovered that drove the human characters mad, and that there was a fiery showdown at the end of the film with a giant live grasshopper... Archaeologists and the military were involved.
Five Million Years to Earth is the movie in question. Found the answer in a search that came up with an IMDB review of the movie.