Thaddeus William Harris, American entomologist and botanist (born 1795)

Thaddeus William Harris was an American entomologist and librarian. His focus on insect life cycles and interactions with plants was influential in broadening American entomological studies beyond a narrow taxonomic approach. He was an early agricultural entomologist and served as a mentor and role model for others in this new field. For 25 years Harris served as the librarian of Harvard University where oversaw the rapid growth of the library and introduced one of the earliest American library card catalogs.