Does "when caught by" mean "when they were caught by"?

Context:

SCARLETT O’HARA was not beautiful, but men seldom realized it when caught by her charm
as the Tarleton twins were. In her face were too sharply blended the delicate features of her mother,
a Coast aristocrat of French descent, and the heavy ones of her florid Irish father. But it was an
arresting face, pointed of chin, square of jaw. Her eyes were pale green without a touch of hazel,
starred with bristly black lashes and slightly tilted at the ends. Above them, her thick black brows
slanted upward, cutting a startling oblique line in her magnolia-white skin—that skin so prized by
Southern women and so carefully guarded with bonnets, veils and mittens against hot Georgia suns.