Ephemera compar is known from a single specimen, collected from the "foothills of Colorado" in 1873, but despite intensive surveys of the Colorado mayflies reported in 1984, it has not been rediscovered.
Ephemera compar coñécese só por un só espécime, recollido en Colorado en 1873, pero na inspección exhaustiva feita en Colorado en 1984 xa non se atopou.