I've posted here saying that wasps had invaded my birdhouses and killed small birds. I also said that I had sprayed the inside with dry teflon, thinking the wasp nest would not stick. Today I removed one of my bird houses and found two nests, one made by a bird and one made by the wasps that chased the bird away. This time I installed some very thin Teflon sheeting to the upper parts of the house. I also had to restore much of the declarations, the sun had eaten them again. I have several more to go.