obstruction vs worm in the apple

obstruction

noun
  • Something which obstructs or impedes, either intentionally or unintentionally 

  • The act of obstructing, or state of being obstructed. 

  • The condition of having the natural powers obstructed in their usual course; the arrest of the vital functions; death. 

worm in the apple

noun
  • A serious flaw in something otherwise good; a problem that ruins everything else. 

How often have the words obstruction and worm in the apple occurred in a corpus of books? (source: Google Ngram Viewer )