The reproductive biology explains much about why this butterfly is facing extirpation and possibly extinction. First, it is single-brooded, with only one opportunity for reproduction a year. If something destroys eggs, caterpillars, or pupae, there are no more chances that year for further breeding.
Males begin emerging from pupation in early June, and females start to emerge a few days later. Males perch on plants and wait for females to fly near. Often, they fly slowly back and forth across prairies in search of emerging females.
Though regal fritillaries mate in early summer, the eggs develop slowly within the female. Regal fritillary mothers do not lay their eggs until late summer or early fall. Females walk through the thick prairie vegetation and deposit eggs singly on various plants, even when the host violets are not near. The eggs hatch in the late summer or fall, but the early-stage caterpillars do not eat; instead, they overwinter in leaf litter.
In spring, the caterpillars come out of hibernation and feed on the tender new leaves of early-spring violets. At this point in the year, the tall, warm-season prairie grasses have not yet grown high enough to shade out the little violet plants. Thus the timing of caterpillar feeding and of their wildflower food plants coincides with the growth cycles of native tallgrass prairies.
The caterpillars grow relatively slowly and enter the chrysalis stage in late spring. The adult males emerge in early summer, then the females, and the cycle begins again.
The unusual timing of egg-laying, hatching, and metamorphosis perfectly fits the cycle of prairie violets, which are only abundant in springtime.