If they are paper wasps that are nesting in the bird house, ER, here's an interesting solution: Rub the birdhouse ceiling with a dry or slightly wet bar of unscented Ivory soap. If a bird nest is present, cover it with paper towels until you're finished. The soap coating prevents wet, pulpy nest-building materials brought in by wasps from sticking to the wood ceiling. You can also cut up the soap, place the pieces in a little water, heat on the stove, cool and apply with a paintbrush.
take a brown paper lunch bag, scrunch the top together and tie closed with a string. (Make it look like something is in the bag) hang it anyplace you don't want a wasp. It looks like a hive and wasps will not go where they think another wasp lives.