bug in ear vs delirium

bug in ear

delirium

noun
  • Wild, frenzied excitement or ecstasy. 

  • A temporary mental state with a sudden onset, usually reversible, including symptoms of confusion, inability to concentrate, disorientation, anxiety, and sometimes hallucinations. Causes can include dehydration, drug intoxication, and severe infection. 

How often have the words bug in ear and delirium occurred in a corpus of books? (source: Google Ngram Viewer )