The work of Preston Jennings set the standard of excellence that has measured all subsequent work on fly-fishing entomology. Born in Wlliamsburg, Virginia, on January 27, 1893 Preston known as "Bobby" to his close friends, began his association with angling by his way of introduction to the sport from an uncle of his. Jennings attended the Medical College of Virginia, now part of the University of Virginia. It is here the we can assume Jennings developed his keen eye of observation, and his scientific approach in studying the ways of the trout. His experiments on how light refracts off a insect on the surface, and how the trout perceives such light, layed the base for his historic fly patterns, "The American March Brown and the Grey Fox".

In 1935 his book entitled "A Book of Trout Flies" gave the American fly-fisherman their long awaited reference to American Trout Stream insects complete with scientific classifications. Thus completing the work that Louis Rhead had begun. This book would go on to become one of the most cherised and highly regarded books in angling history. One of the key aspcects of Jennings is that he was equally at home on the trout stream, as he was in the lab. A highly regarded angler and fly tier, his work and contributions are legendary.