Predator avoidance is often a key factor in the behavior of North American cicadas. In the protoperiodical genus OkanaganaDistant, 1905, several species synchronize emergences based on a cumulative rainfall emergence threshold, avoiding predators via a selfish herd. One of these species, O. magnificaDavis, 1919, extends its range beyond that of its synchronizing cohorts. The hypothesis is tested that outside of sympatry with these species, O. magnifica would lose a rainfall-based emergence pattern. Using multiple databases, locations of consecutive emergences of O. magnifica are identified. The cumulative rainfall between emergences is calculated and compared to a known emergence threshold of 1181 millimeters. The results show that non-sympatric populations have a protoperiodical lifecycle that is independent of rainfall yet does not follow a strict resource accumulation phenology. These two strategies form allochronically isolated populations with a boundary reinforced by the presence of co-synchronizing species.