All genders of the insect are called by the same name. They are beetles. Ladybugs are also known as "ladybirds" or "lady beetles." So how did the term “lady" get attached to these insects? Many people believe the term “lady" refers to the Virgin Mary, who is often referred to as “Our Lady."
The Virgin Mary was often portrayed wearing a red cloak in early paintings. Scholars believe European farmers came up with the term “Beetle of Our Lady" after they prayed to the Virgin Mary to save their crops from pests and noticed that a tiny red beetle came to eat the insects hurting their crops. Ladybirds are particularly fond of aphids.
Some fun facts to while away your hours :-)
Hello :) I thought that if more than one colours are used as adjectives to describe a feminine subject they all revert to the masculine spelling. Is that not the case here because there are only 2 colours used separated by "et"? In other words, if 3 colours were used to describe the ladybug would the masculine versions be correct?
You are confusing it with compound adjectives used to describe a single colour such as "light blue" = bleu clair. These are invariable.
"The light blue skirts" → "Les jupes bleu clair ".
As you can see, neither adjective is plural or feminine as it is a compound adjective so therefore invariable (ie singular and masculine).