The term "lady" refers to the Virgin Mary. According to legend, crops in Europe during the Middle Ages were plagued by pests, and farmers began praying to the blessed Lady Mary. Ladybugs then appeared in the fields, miraculously saving the crops, causing the farmers to call them lady beetles.
The name "ladybug" was associated with the Virgin Mary in the Middle Ages. The Virgin Mary was often depicted in a red cloak, and the seven-spotted ladybug is believed to have been named for her. Its color is said to represent her cloak, while the black spots represent her seven sorrows.