Bug vs Mole

Bug

name
  • A river in Ukraine (Southern Bug), flowing 530 miles to the Dnieper estuary. 

  • A river flowing northwest 450 miles between Belarus and Poland. 

noun
  • A Bugatti car. 

  • A Volkswagen Beetle car. 

Mole

name
  • A river in Surrey, England, tributary to the Thames. 

  • A river in Devon, England, tributary to the Taw. 

  • A surname. 

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