Odd word, yes, but farmers used to believe that those useful insects were a gift from St. Mary - hence Marienkäfer in German, ladybird/ladybug in English, mariquita (little Mary) in Spanish, and so on.
The French "bête à bon Dieu" is a little different but comes with an even
better story.

Some time in the Middle Ages, a man was to be beheaded. He had said many times that he was innocent, but ... So when his head was placed on the block, a ladybird came to sit right on his neck. The executioner tried to move it away, but it would come back and land on the very same spot, again and again. Ultimately the king considered this to be a divine intervention and pardoned the guy. Even better, a few days later the actual crinimal was caught ...
Christian