His death was announced by Montana State University, where he served as president from 1970 to 1977. The cause was not given.
McIntosh, who retired to Bozeman, returned to the public eye in 2008 when he donated his boyhood beetle collection to Montana State.
McIntosh said last fall that he once considered entomology as a career, but he found that he enjoyed public speaking even more than insects.
McIntosh was born in Redlands on Dec. 1, 1914, and received his bachelor's degree from the University of Redlands, where he excelled at debating. He received his master's and doctoral degrees from what is now the University of Iowa.
He began teaching speech in 1939 at the University of Idaho's Pocatello branch and served in the Army in Europe during World War II. After the war he returned to Pocatello and became president of the school in 1947, when it became Idaho State College.
In 1959 he was named president of what was then Long Beach State College, remaining until 1969. During his tenure, enrollment increased from 10,000 students in 1960 to 20,000 by 1966, according to a history on the university website. He also oversaw a number of capital improvements to accommodate more students and faculty and expanded the range of degree and course offerings. The McIntosh Humanities Building is named for him.
McIntosh was able to live alone with the help of friends, a Lifeline button, Meals on Wheels and deliveries from the Bozeman Public Library.
McIntosh, who was divorced, is survived by a daughter, Diana, of Portland, Ore., and two grandchildren. No services are planned.