The easiest way to deal with wasps is with some dry ice at night. leave a few hunks around the ground where they nest. The dry ice will suffocate them as they sleep.
With a bit of poking around the web, one can find plans to build a cold version of a flamethrower, which is great for hanging nests. Wait until the night.. Carefully insert nozzle.. Pull trigger... and Waspcicles !!! once the hanging nest has a healthy frost coating the outside, cut it down and toss it into a fire, or just smash the hell out of it with a bat -- either are fun to do.
I wont post any dry ice gun plans here, because they can be dangerous if poorly constructed - and a primitive may decide to raise a stink if their failed experiment results in frostbite, or injury from explosion.