I wondered why Chickadees had not revisited a  newly excavated cavity
for a few days.  Last night's closer inspection  revealed the beginning 
of a Paper Wasp nest, a Polistes species (Polistes  dominula) --
wasp nest and wasp tweezed to oblivion.

I'm  accustomed to removing the occasional mud-dauber wasp nest from 
a Cliff  Swallow nest, but in recent years, the primary problem has been
paper wasp  nests.  After not having cleaned swallow nests last year, 
this winter,  I found ALL nine old swallow nests on the south end 
of my house to be packed  solid with paper, and removed the paper. 
Last autumn, one  room in each of three metal Purple Martin houses 
also contained a large wasp  nest -- explaining why the Tree Swallow pair 
had switched to different room  than the one they had always used.  

D J Hoag, Grand Isle