thumb|right|Cyrus Thomas
Cyrus Thomas (July 27, 1825 – June 26, 1910) was an American ethnologist and entomologist prominent in the late 19th century and noted for his studies of the natural history of the American West.
Biography
thumb|left|Cyrus Thomas - During 1870 Hayden survey
Thomas was born in Kingsport, Tennessee, on July 27, 1825, and was of German and Irish descent.
From 1851 to 1854 Thomas served as county clerk of Jackson County, Illinois. He later abandoned the practice of law, and in 1865 became superintendent of some Jackson County schools. This lasted only for a few years. Also during this time he entered the ministry of the Evangelical Lutheran Church, but was forced to abandon the ministry, as well, due to his "intense independent thought".
In 1873 Thomas was appointed a professor of natural science at Southern Illinois Normal University, which gave him a public forum for his ideas. He was later named to the United States Entomological Commission in 1877 to serve alongside Charles Valentine Riley and Alpheus Spring Packard; at the same time he accepted the position of chief entomologist for the State of Illinois, where he succeeded William LeBaron. He kept his title of chief entomologist until 1882 after the commission came to an end in 1879. At this time, 1882, he was appointed archaeologist to the United States Bureau of American Ethnology.
Thomas was married twice, having lost his first wife, Dorthy Logan, sister of Maj. Gen.and later U.S. Senator John A. Logan. He remarried in 1865 to Viola L. Davis. With her, he fathered five girls and one boy, who died in infancy. Thomas died on June 26, 1910, and was buried in Frederick, Maryland.
Works
Entomology
Thomas made some noteworthy contributions as an entomologist, having helped control the insect plague that was slowing the growth rate of the border states. Thomas, working with Charles V. Riley, found that the Hessian fly, which was terrorizing the wheat and rye of the western states, was most destructive in wet seasons and least destructive in dry seasons. With this information they were able to predict the outbreaks rather accurately for the upcoming year, and entomologists and farmers worked together for better times to plant and harvest.
The chinch bug was another culprit damaging crops. Thomas and LeBaron, using the same tactic of studying the chinch bug's relationship to the weather, found that chinch bugs needed at least one or two dry seasons to reach outbreak proportions. Thomas found a pattern between the chinch bug and weather, concluding that outbreaks can be expected about every seven years and then for two years in a row.
Thomas divided the mounds into a northern section, which was divided into six sections, and a southern section, which was divided into two. Thomas thought that migration was the reason for the mounds being spread through the east, but also recognized that the idea for mounds diffused through the different tribes.