caterpillar vs crawler

caterpillar

noun
  • A vehicle with a caterpillar track; a crawler 

  • The larva of a butterfly or moth; leafworm 

  • A set of subtrees of a tree 

crawler

noun
  • A tractor crawler, a motorized vehicle that uses caterpillar tracks instead of wheels. 

  • A child who is able to creep using its hands and knees but is not able to walk. 

  • A crawl swimmer. 

  • A mobile stage in the development of stationary hemipteran insects such as scale insects—generally the first instar. 

  • A sycophant. 

  • A software bot that autonomously follows connected paths such as links between web pages. 

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