With a title mentioning cannibal ants and a bunker, I'm surprised no-one has referenced Phase IV yet, but given it was a box office flop from 1974. I've not watched it in so long, but I seem to remember it being quite scary as a kid and the fact I still remember it now. On the offchance anyone remembers it or watches it I'd be curious what you think? https://www.imdb.com/title/tt0070531/