A key was developed using morphological and behavioral characters to identify nine genera and 13 species of protists found in the hindgut of three Reticulitermes species— Reticulitermes flavipes (Kollar), Reticulitermes virginicus (Banks), and Reticulitermes hageni Banks—by using the online IDnature guides by Discover Life. There are seven characters and 13 taxa, each attached to species descriptions, digital stills, or movies to aid in protist species identification. We chose characters for protist species identification that were easy to observe with live samples and a light microscope at 400× magnification. All 11 protists from R. flavipes and nine each in R. virginicus and R. hageni were recognized using original and revised species descriptions. This was the first report of the protist genera Trichomitus from both R. virginicus and R. hageni.