Fritillaries can be very tough to ID, but not this one. The dark one is the female …and since they are mating, there is no question that the other is the male Great Spangled Fritillary. As you can see on the female, they have a very wide band separating the inner and outer portion of the underside of the wings. This makes them probably the easiest fritillary to identify (as long as you can see it). This species flies throughout much of North America in open areas, moist fields, and prairies. Caterpillars feed on leaves of violets.  

Photo by: Kathy Mackey on 7/20/21 in Missoula, MT