This time, the insects trying to destroy humanity aren't giant ones. It's all of them, though, which is worse.
Like most well-made science fiction movies, this has a strong symbolic component, rendering it a fable or parable. Here, the thought is that mankind is being destroyed by its inability to communicate and thus cooperate. American soldiers are looking for "Eastern bloc" spies, and try to find a lost H-bomb without anyone finding out; the blonde lady who's using the insects hates people; a girl thinks of having an abortion, because she doesn't know that her lover wants it.
Some characters can't be found, some won't talk, resulting in a solution being impossible to arrive at. Normally I would call this idiot plotting, a problem that wouldn't be a problem if people talked. Here, that's the point of this movie: problems are caused by people not talking.
