Some birds eat wasps, Amos, and enjoy them thoroughly. I can't remember which type of bird it is, but they do. Also, various forms of wasps and hornets will fight vicious territorial battles with neighbouring hives from time to time, so there are numerous violent threats to a wasp's existence.

If you intend harm to a wasp's nest, they're usually pretty sharp at detecting it...even when you're not too close yet. That's why you'd better darned well plan your attack in the best strategic way (like after darkness falls).

There's a good deal of evidence to suggest that wasps, bees, ants, and other hive animals share a sort of group mind. If you get the attention of some hive members in any serious way, the whole hive is often alerted almost instantaneously. I've seen this with ants, and it's very interesting. Disturb some of the ones on the surface of a hive, and the whole hive can become agitated in an amazingly short period of time, and many more ants will come running out from underground.

Another interesting example of the possible effects of group consciousness at work: Watch how a huge flock of birds veers and suddenly changes direction in midair, as if they all got the idea at once. They become almost like a single multi-celled organism of some kind.