Asa Fitch (February 24, 1809 – April 8, 1879) was a natural historian and entomologist from Salem, New York.

Asa Fitch was born at Fitch's Point, Salem, New York on February 24, 1809.^[1] His early studies were of both natural history and medicine, which he studied at the newly formed Rensselaer Polytechnic Institute, graduating in 1827. However, in 1838 he decided to start studying agriculture and entomology. In 1838 he began to collect and study insects for New York state. In 1854 he became the first professional entomologist of New York State Agricultural Society (commissioned by the State of New York). This made him the first occupational entomologist in the United States.

His vast studies of many insects helped scientists to solve some of the problems of crop damage caused by insects. Many of his notebooks are now the property of the Smithsonian Institution. Fitch also discovered the rodent botfly Cuterebra emasculator in 1856. He died April 8, 1879, at his home in Salem, New York.^[2]

The Martin–Fitch House and Asa Fitch Jr. Laboratory was added to the National Register of Historic Places in 2014.^[3]