Question: Why do ladybirds have spots

Alex Batchelor answered on 18 Nov 2019:

The bright red and the black spots are actually a warning to things that might eat the ladybird that ladybirds are poisonous or taste bad. If any animals eat them learn that things that colour taste awful or make them sick so they don’t eat any other ladybirds.

Using colours as a warning to predators is called aposematism.