The name "ladybird" originated in Britain where the insects became known as "Our Lady's bird" or the "Lady beetle". That's written in the Wikipedia. Without this information, I still have no objection about the name. The shiny red color and the black polka dots make the beetle so beautiful. Let us do it this way.
The red and black beetle is beautiful.
Lady is beautiful.
So the beetle is a lady.
I guess, that's why it's called "Ladybird".. Ohhh..whatever!