I potted the buddleia stem and made an enclosure of wooden chopsticks and cheesecloth to keep out predators. By 7:23 P.M., when this photo was taken, a half-inch segment of the edge of the leaf was tightly rolled up.

Buddleia will grow from woody cuttings. If it also grows from stem cuttings, an identifiable moth may emerge. I don't know whether successful pupation requires a living plant. On the parent plant and other buddleias here that are infested with these larvae, many leaves have similar rolled-up edges. I welcome suggestions about isolating the cocoons in order to see what comes out.