McCook was born in
New Lisbon, Ohio, to
Dr. John McCook and Julia Sheldon McCook. He learned the printing trade as a youth, then taught school for several years and attended
Jefferson College. He was a member of the
Franklin Literary Society and founded the chapter of
Theta Delta Chi at Jefferson College. After graduation in 1859, he studied theology privately and in the
Western Theological Seminary in
Allegheny, Pennsylvania. With the outbreak of the Civil War, he enlisted in the
41st Illinois Volunteer Infantry Regiment as a
chaplain with the rank of
first lieutenant and helped tend the wounded. As a minister in
Clinton, Illinois,
St. Louis, and
Steubenville, Ohio, McCook became known for his compassion and intellect, and for his leadership in the movement to create
Sunday Schools. In 1869, he became pastor of the Seventh Presbyterian church of
Philadelphia, where he lived for the rest of his life. He spent his summers studying the behavior of
ants and
spiders. He published his observations and discoveries in a number of journals and books, as well as in a series of well-received illustrated children's books that explained the insects characteristics and traits in language and drawings for young minds. Many of McCook's books used illustrations drawn by
Daniel Carter Beard, the founder of the
Boy Scouts of America. In the summer of 1877, he travelled to
Texas to study agricultural ants. Two years later, McCook wrote
The Natural History of the Agricultural Ant of Texas. In 1889–93, he published his most ambitious work,
American Spiders and Their Spinning Work, in three illustrated volumes. He also wrote a book on his ancestors in the
Whiskey Rebellion, and delivered a number of papers on Civil War history at meetings of the
Military Order of the Loyal Legion of the United States veterans organization. McCook was Vice President of both the
American Entomological Society and the
Academy of Natural Sciences. In 1880,
Lafayette College conferred the degree of
Doctor of Divinity to McCook. In 1895, he designed the official flag of the city of Philadelphia. He was elected to the
American Philosophical Society in 1896. He again served as an Army Chaplain during the
Spanish–American War in 1898. ==McCook's works==