journal articleAttempts to provide keys to the families and subfamilies of Ephemeroptera nymphs in general entomology textbooks (i.e. Essig (1942), Chu (1949), and Brues, Melander and Carpenter (1954)) have been far from satisfactory. This difficulty exists largely because of the failure of specialists of the Ephemeroptera to provide keys of world-wide application that are sufficiently illustrated to be of value to non-specialists. In the last few decades, however, there have been many figures published that will aid any person attempting to construct such keys. Excellent figures of a variety of families are found in such works as those of Barnard (1932), Spieth (1933), Needham, Traver and Hsu (1935), Ulmer (1940), Crass (1947), Berner (1950), Tshernova (1952), and Burks (1953)
