There is no convention or consistency in the naming of artificial flies. Long-standing popular patterns have names that have persisted over time. However, fly designers and amateur or professional fly tyers are free to create any fly they choose and to give it any name they want.
The absence of a widely accepted naming convention for artificial flies means that popular designs continue to bear their traditional names. In contrast, individuals involved in designing or tying flies have the liberty to create unique patterns and assign whatever name they desire.